Merge branch 'drm-next-5.1' of git://people.freedesktop.org/~agd5f/linux into drm...

[thirdparty/kernel/stable.git] / drivers / gpu / drm / i915 / intel_ringbuffer.c

/*
 * Copyright © 2008-2010 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *    Zou Nan hai <nanhai.zou@intel.com>
 *    Xiang Hai hao<haihao.xiang@intel.com>
 *
 */

#include <linux/log2.h>

#include <drm/i915_drm.h>

#include "i915_drv.h"
#include "i915_gem_render_state.h"
#include "i915_reset.h"
#include "i915_trace.h"
#include "intel_drv.h"
#include "intel_workarounds.h"

/* Rough estimate of the typical request size, performing a flush,
 * set-context and then emitting the batch.
 */
#define LEGACY_REQUEST_SIZE 200

static inline u32 intel_hws_seqno_address(struct intel_engine_cs *engine)
{
        return (i915_ggtt_offset(engine->status_page.vma) +
                I915_GEM_HWS_INDEX_ADDR);
}

unsigned int intel_ring_update_space(struct intel_ring *ring)
{
        unsigned int space;

        space = __intel_ring_space(ring->head, ring->emit, ring->size);

        ring->space = space;
        return space;
}

static int
gen2_render_ring_flush(struct i915_request *rq, u32 mode)
{
        unsigned int num_store_dw;
        u32 cmd, *cs;

        cmd = MI_FLUSH;
        num_store_dw = 0;
        if (mode & EMIT_INVALIDATE)
                cmd |= MI_READ_FLUSH;
        if (mode & EMIT_FLUSH)
                num_store_dw = 4;

        cs = intel_ring_begin(rq, 2 + 3 * num_store_dw);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = cmd;
        while (num_store_dw--) {
                *cs++ = MI_STORE_DWORD_IMM | MI_MEM_VIRTUAL;
                *cs++ = i915_scratch_offset(rq->i915);
                *cs++ = 0;
        }
        *cs++ = MI_FLUSH | MI_NO_WRITE_FLUSH;

        intel_ring_advance(rq, cs);

        return 0;
}

static int
gen4_render_ring_flush(struct i915_request *rq, u32 mode)
{
        u32 cmd, *cs;
        int i;

        /*
         * read/write caches:
         *
         * I915_GEM_DOMAIN_RENDER is always invalidated, but is
         * only flushed if MI_NO_WRITE_FLUSH is unset.  On 965, it is
         * also flushed at 2d versus 3d pipeline switches.
         *
         * read-only caches:
         *
         * I915_GEM_DOMAIN_SAMPLER is flushed on pre-965 if
         * MI_READ_FLUSH is set, and is always flushed on 965.
         *
         * I915_GEM_DOMAIN_COMMAND may not exist?
         *
         * I915_GEM_DOMAIN_INSTRUCTION, which exists on 965, is
         * invalidated when MI_EXE_FLUSH is set.
         *
         * I915_GEM_DOMAIN_VERTEX, which exists on 965, is
         * invalidated with every MI_FLUSH.
         *
         * TLBs:
         *
         * On 965, TLBs associated with I915_GEM_DOMAIN_COMMAND
         * and I915_GEM_DOMAIN_CPU in are invalidated at PTE write and
         * I915_GEM_DOMAIN_RENDER and I915_GEM_DOMAIN_SAMPLER
         * are flushed at any MI_FLUSH.
         */

        cmd = MI_FLUSH;
        if (mode & EMIT_INVALIDATE) {
                cmd |= MI_EXE_FLUSH;
                if (IS_G4X(rq->i915) || IS_GEN(rq->i915, 5))
                        cmd |= MI_INVALIDATE_ISP;
        }

        i = 2;
        if (mode & EMIT_INVALIDATE)
                i += 20;

        cs = intel_ring_begin(rq, i);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = cmd;

        /*
         * A random delay to let the CS invalidate take effect? Without this
         * delay, the GPU relocation path fails as the CS does not see
         * the updated contents. Just as important, if we apply the flushes
         * to the EMIT_FLUSH branch (i.e. immediately after the relocation
         * write and before the invalidate on the next batch), the relocations
         * still fail. This implies that is a delay following invalidation
         * that is required to reset the caches as opposed to a delay to
         * ensure the memory is written.
         */
        if (mode & EMIT_INVALIDATE) {
                *cs++ = GFX_OP_PIPE_CONTROL(4) | PIPE_CONTROL_QW_WRITE;
                *cs++ = i915_scratch_offset(rq->i915) | PIPE_CONTROL_GLOBAL_GTT;
                *cs++ = 0;
                *cs++ = 0;

                for (i = 0; i < 12; i++)
                        *cs++ = MI_FLUSH;

                *cs++ = GFX_OP_PIPE_CONTROL(4) | PIPE_CONTROL_QW_WRITE;
                *cs++ = i915_scratch_offset(rq->i915) | PIPE_CONTROL_GLOBAL_GTT;
                *cs++ = 0;
                *cs++ = 0;
        }

        *cs++ = cmd;

        intel_ring_advance(rq, cs);

        return 0;
}

/*
 * Emits a PIPE_CONTROL with a non-zero post-sync operation, for
 * implementing two workarounds on gen6.  From section 1.4.7.1
 * "PIPE_CONTROL" of the Sandy Bridge PRM volume 2 part 1:
 *
 * [DevSNB-C+{W/A}] Before any depth stall flush (including those
 * produced by non-pipelined state commands), software needs to first
 * send a PIPE_CONTROL with no bits set except Post-Sync Operation !=
 * 0.
 *
 * [Dev-SNB{W/A}]: Before a PIPE_CONTROL with Write Cache Flush Enable
 * =1, a PIPE_CONTROL with any non-zero post-sync-op is required.
 *
 * And the workaround for these two requires this workaround first:
 *
 * [Dev-SNB{W/A}]: Pipe-control with CS-stall bit set must be sent
 * BEFORE the pipe-control with a post-sync op and no write-cache
 * flushes.
 *
 * And this last workaround is tricky because of the requirements on
 * that bit.  From section 1.4.7.2.3 "Stall" of the Sandy Bridge PRM
 * volume 2 part 1:
 *
 *     "1 of the following must also be set:
 *      - Render Target Cache Flush Enable ([12] of DW1)
 *      - Depth Cache Flush Enable ([0] of DW1)
 *      - Stall at Pixel Scoreboard ([1] of DW1)
 *      - Depth Stall ([13] of DW1)
 *      - Post-Sync Operation ([13] of DW1)
 *      - Notify Enable ([8] of DW1)"
 *
 * The cache flushes require the workaround flush that triggered this
 * one, so we can't use it.  Depth stall would trigger the same.
 * Post-sync nonzero is what triggered this second workaround, so we
 * can't use that one either.  Notify enable is IRQs, which aren't
 * really our business.  That leaves only stall at scoreboard.
 */
static int
gen6_emit_post_sync_nonzero_flush(struct i915_request *rq)
{
        u32 scratch_addr = i915_scratch_offset(rq->i915) + 2 * CACHELINE_BYTES;
        u32 *cs;

        cs = intel_ring_begin(rq, 6);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = GFX_OP_PIPE_CONTROL(5);
        *cs++ = PIPE_CONTROL_CS_STALL | PIPE_CONTROL_STALL_AT_SCOREBOARD;
        *cs++ = scratch_addr | PIPE_CONTROL_GLOBAL_GTT;
        *cs++ = 0; /* low dword */
        *cs++ = 0; /* high dword */
        *cs++ = MI_NOOP;
        intel_ring_advance(rq, cs);

        cs = intel_ring_begin(rq, 6);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = GFX_OP_PIPE_CONTROL(5);
        *cs++ = PIPE_CONTROL_QW_WRITE;
        *cs++ = scratch_addr | PIPE_CONTROL_GLOBAL_GTT;
        *cs++ = 0;
        *cs++ = 0;
        *cs++ = MI_NOOP;
        intel_ring_advance(rq, cs);

        return 0;
}

static int
gen6_render_ring_flush(struct i915_request *rq, u32 mode)
{
        u32 scratch_addr = i915_scratch_offset(rq->i915) + 2 * CACHELINE_BYTES;
        u32 *cs, flags = 0;
        int ret;

        /* Force SNB workarounds for PIPE_CONTROL flushes */
        ret = gen6_emit_post_sync_nonzero_flush(rq);
        if (ret)
                return ret;

        /* Just flush everything.  Experiments have shown that reducing the
         * number of bits based on the write domains has little performance
         * impact.
         */
        if (mode & EMIT_FLUSH) {
                flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
                /*
                 * Ensure that any following seqno writes only happen
                 * when the render cache is indeed flushed.
                 */
                flags |= PIPE_CONTROL_CS_STALL;
        }
        if (mode & EMIT_INVALIDATE) {
                flags |= PIPE_CONTROL_TLB_INVALIDATE;
                flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
                /*
                 * TLB invalidate requires a post-sync write.
                 */
                flags |= PIPE_CONTROL_QW_WRITE | PIPE_CONTROL_CS_STALL;
        }

        cs = intel_ring_begin(rq, 4);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = GFX_OP_PIPE_CONTROL(4);
        *cs++ = flags;
        *cs++ = scratch_addr | PIPE_CONTROL_GLOBAL_GTT;
        *cs++ = 0;
        intel_ring_advance(rq, cs);

        return 0;
}

static u32 *gen6_rcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
{
        /* First we do the gen6_emit_post_sync_nonzero_flush w/a */
        *cs++ = GFX_OP_PIPE_CONTROL(4);
        *cs++ = PIPE_CONTROL_CS_STALL | PIPE_CONTROL_STALL_AT_SCOREBOARD;
        *cs++ = 0;
        *cs++ = 0;

        *cs++ = GFX_OP_PIPE_CONTROL(4);
        *cs++ = PIPE_CONTROL_QW_WRITE;
        *cs++ = i915_scratch_offset(rq->i915) | PIPE_CONTROL_GLOBAL_GTT;
        *cs++ = 0;

        /* Finally we can flush and with it emit the breadcrumb */
        *cs++ = GFX_OP_PIPE_CONTROL(4);
        *cs++ = (PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH |
                 PIPE_CONTROL_DEPTH_CACHE_FLUSH |
                 PIPE_CONTROL_DC_FLUSH_ENABLE |
                 PIPE_CONTROL_QW_WRITE |
                 PIPE_CONTROL_CS_STALL);
        *cs++ = rq->timeline->hwsp_offset | PIPE_CONTROL_GLOBAL_GTT;
        *cs++ = rq->fence.seqno;

        *cs++ = GFX_OP_PIPE_CONTROL(4);
        *cs++ = PIPE_CONTROL_QW_WRITE | PIPE_CONTROL_CS_STALL;
        *cs++ = intel_hws_seqno_address(rq->engine) | PIPE_CONTROL_GLOBAL_GTT;
        *cs++ = rq->global_seqno;

        *cs++ = MI_USER_INTERRUPT;
        *cs++ = MI_NOOP;

        rq->tail = intel_ring_offset(rq, cs);
        assert_ring_tail_valid(rq->ring, rq->tail);

        return cs;
}

static int
gen7_render_ring_cs_stall_wa(struct i915_request *rq)
{
        u32 *cs;

        cs = intel_ring_begin(rq, 4);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = GFX_OP_PIPE_CONTROL(4);
        *cs++ = PIPE_CONTROL_CS_STALL | PIPE_CONTROL_STALL_AT_SCOREBOARD;
        *cs++ = 0;
        *cs++ = 0;
        intel_ring_advance(rq, cs);

        return 0;
}

static int
gen7_render_ring_flush(struct i915_request *rq, u32 mode)
{
        u32 scratch_addr = i915_scratch_offset(rq->i915) + 2 * CACHELINE_BYTES;
        u32 *cs, flags = 0;

        /*
         * Ensure that any following seqno writes only happen when the render
         * cache is indeed flushed.
         *
         * Workaround: 4th PIPE_CONTROL command (except the ones with only
         * read-cache invalidate bits set) must have the CS_STALL bit set. We
         * don't try to be clever and just set it unconditionally.
         */
        flags |= PIPE_CONTROL_CS_STALL;

        /* Just flush everything.  Experiments have shown that reducing the
         * number of bits based on the write domains has little performance
         * impact.
         */
        if (mode & EMIT_FLUSH) {
                flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DC_FLUSH_ENABLE;
                flags |= PIPE_CONTROL_FLUSH_ENABLE;
        }
        if (mode & EMIT_INVALIDATE) {
                flags |= PIPE_CONTROL_TLB_INVALIDATE;
                flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_MEDIA_STATE_CLEAR;
                /*
                 * TLB invalidate requires a post-sync write.
                 */
                flags |= PIPE_CONTROL_QW_WRITE;
                flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;

                flags |= PIPE_CONTROL_STALL_AT_SCOREBOARD;

                /* Workaround: we must issue a pipe_control with CS-stall bit
                 * set before a pipe_control command that has the state cache
                 * invalidate bit set. */
                gen7_render_ring_cs_stall_wa(rq);
        }

        cs = intel_ring_begin(rq, 4);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = GFX_OP_PIPE_CONTROL(4);
        *cs++ = flags;
        *cs++ = scratch_addr;
        *cs++ = 0;
        intel_ring_advance(rq, cs);

        return 0;
}

static u32 *gen7_rcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
{
        *cs++ = GFX_OP_PIPE_CONTROL(4);
        *cs++ = (PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH |
                 PIPE_CONTROL_DEPTH_CACHE_FLUSH |
                 PIPE_CONTROL_DC_FLUSH_ENABLE |
                 PIPE_CONTROL_FLUSH_ENABLE |
                 PIPE_CONTROL_QW_WRITE |
                 PIPE_CONTROL_GLOBAL_GTT_IVB |
                 PIPE_CONTROL_CS_STALL);
        *cs++ = rq->timeline->hwsp_offset;
        *cs++ = rq->fence.seqno;

        *cs++ = GFX_OP_PIPE_CONTROL(4);
        *cs++ = (PIPE_CONTROL_QW_WRITE |
                 PIPE_CONTROL_GLOBAL_GTT_IVB |
                 PIPE_CONTROL_CS_STALL);
        *cs++ = intel_hws_seqno_address(rq->engine);
        *cs++ = rq->global_seqno;

        *cs++ = MI_USER_INTERRUPT;
        *cs++ = MI_NOOP;

        rq->tail = intel_ring_offset(rq, cs);
        assert_ring_tail_valid(rq->ring, rq->tail);

        return cs;
}

static u32 *gen6_xcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
{
        GEM_BUG_ON(rq->timeline->hwsp_ggtt != rq->engine->status_page.vma);
        GEM_BUG_ON(offset_in_page(rq->timeline->hwsp_offset) != I915_GEM_HWS_SEQNO_ADDR);

        *cs++ = MI_FLUSH_DW | MI_FLUSH_DW_OP_STOREDW | MI_FLUSH_DW_STORE_INDEX;
        *cs++ = I915_GEM_HWS_SEQNO_ADDR | MI_FLUSH_DW_USE_GTT;
        *cs++ = rq->fence.seqno;

        *cs++ = MI_FLUSH_DW | MI_FLUSH_DW_OP_STOREDW | MI_FLUSH_DW_STORE_INDEX;
        *cs++ = I915_GEM_HWS_INDEX_ADDR | MI_FLUSH_DW_USE_GTT;
        *cs++ = rq->global_seqno;

        *cs++ = MI_USER_INTERRUPT;
        *cs++ = MI_NOOP;

        rq->tail = intel_ring_offset(rq, cs);
        assert_ring_tail_valid(rq->ring, rq->tail);

        return cs;
}

#define GEN7_XCS_WA 32
static u32 *gen7_xcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
{
        int i;

        GEM_BUG_ON(rq->timeline->hwsp_ggtt != rq->engine->status_page.vma);
        GEM_BUG_ON(offset_in_page(rq->timeline->hwsp_offset) != I915_GEM_HWS_SEQNO_ADDR);

        *cs++ = MI_FLUSH_DW | MI_FLUSH_DW_OP_STOREDW | MI_FLUSH_DW_STORE_INDEX;
        *cs++ = I915_GEM_HWS_SEQNO_ADDR | MI_FLUSH_DW_USE_GTT;
        *cs++ = rq->fence.seqno;

        *cs++ = MI_FLUSH_DW | MI_FLUSH_DW_OP_STOREDW | MI_FLUSH_DW_STORE_INDEX;
        *cs++ = I915_GEM_HWS_INDEX_ADDR | MI_FLUSH_DW_USE_GTT;
        *cs++ = rq->global_seqno;

        for (i = 0; i < GEN7_XCS_WA; i++) {
                *cs++ = MI_STORE_DWORD_INDEX;
                *cs++ = I915_GEM_HWS_SEQNO_ADDR;
                *cs++ = rq->fence.seqno;
        }

        *cs++ = MI_FLUSH_DW;
        *cs++ = 0;
        *cs++ = 0;

        *cs++ = MI_USER_INTERRUPT;

        rq->tail = intel_ring_offset(rq, cs);
        assert_ring_tail_valid(rq->ring, rq->tail);

        return cs;
}
#undef GEN7_XCS_WA

static void set_hwstam(struct intel_engine_cs *engine, u32 mask)
{
        /*
         * Keep the render interrupt unmasked as this papers over
         * lost interrupts following a reset.
         */
        if (engine->class == RENDER_CLASS) {
                if (INTEL_GEN(engine->i915) >= 6)
                        mask &= ~BIT(0);
                else
                        mask &= ~I915_USER_INTERRUPT;
        }

        intel_engine_set_hwsp_writemask(engine, mask);
}

static void set_hws_pga(struct intel_engine_cs *engine, phys_addr_t phys)
{
        struct drm_i915_private *dev_priv = engine->i915;
        u32 addr;

        addr = lower_32_bits(phys);
        if (INTEL_GEN(dev_priv) >= 4)
                addr |= (phys >> 28) & 0xf0;

        I915_WRITE(HWS_PGA, addr);
}

static struct page *status_page(struct intel_engine_cs *engine)
{
        struct drm_i915_gem_object *obj = engine->status_page.vma->obj;

        GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
        return sg_page(obj->mm.pages->sgl);
}

static void ring_setup_phys_status_page(struct intel_engine_cs *engine)
{
        set_hws_pga(engine, PFN_PHYS(page_to_pfn(status_page(engine))));
        set_hwstam(engine, ~0u);
}

static void set_hwsp(struct intel_engine_cs *engine, u32 offset)
{
        struct drm_i915_private *dev_priv = engine->i915;
        i915_reg_t hwsp;

        /*
         * The ring status page addresses are no longer next to the rest of
         * the ring registers as of gen7.
         */
        if (IS_GEN(dev_priv, 7)) {
                switch (engine->id) {
                /*
                 * No more rings exist on Gen7. Default case is only to shut up
                 * gcc switch check warning.
                 */
                default:
                        GEM_BUG_ON(engine->id);
                case RCS:
                        hwsp = RENDER_HWS_PGA_GEN7;
                        break;
                case BCS:
                        hwsp = BLT_HWS_PGA_GEN7;
                        break;
                case VCS:
                        hwsp = BSD_HWS_PGA_GEN7;
                        break;
                case VECS:
                        hwsp = VEBOX_HWS_PGA_GEN7;
                        break;
                }
        } else if (IS_GEN(dev_priv, 6)) {
                hwsp = RING_HWS_PGA_GEN6(engine->mmio_base);
        } else {
                hwsp = RING_HWS_PGA(engine->mmio_base);
        }

        I915_WRITE(hwsp, offset);
        POSTING_READ(hwsp);
}

static void flush_cs_tlb(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        i915_reg_t instpm = RING_INSTPM(engine->mmio_base);

        if (!IS_GEN_RANGE(dev_priv, 6, 7))
                return;

        /* ring should be idle before issuing a sync flush*/
        WARN_ON((I915_READ_MODE(engine) & MODE_IDLE) == 0);

        I915_WRITE(instpm,
                   _MASKED_BIT_ENABLE(INSTPM_TLB_INVALIDATE |
                                      INSTPM_SYNC_FLUSH));
        if (intel_wait_for_register(dev_priv,
                                    instpm, INSTPM_SYNC_FLUSH, 0,
                                    1000))
                DRM_ERROR("%s: wait for SyncFlush to complete for TLB invalidation timed out\n",
                          engine->name);
}

static void ring_setup_status_page(struct intel_engine_cs *engine)
{
        set_hwsp(engine, i915_ggtt_offset(engine->status_page.vma));
        set_hwstam(engine, ~0u);

        flush_cs_tlb(engine);
}

static bool stop_ring(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        if (INTEL_GEN(dev_priv) > 2) {
                I915_WRITE_MODE(engine, _MASKED_BIT_ENABLE(STOP_RING));
                if (intel_wait_for_register(dev_priv,
                                            RING_MI_MODE(engine->mmio_base),
                                            MODE_IDLE,
                                            MODE_IDLE,
                                            1000)) {
                        DRM_ERROR("%s : timed out trying to stop ring\n",
                                  engine->name);
                        /* Sometimes we observe that the idle flag is not
                         * set even though the ring is empty. So double
                         * check before giving up.
                         */
                        if (I915_READ_HEAD(engine) != I915_READ_TAIL(engine))
                                return false;
                }
        }

        I915_WRITE_HEAD(engine, I915_READ_TAIL(engine));

        I915_WRITE_HEAD(engine, 0);
        I915_WRITE_TAIL(engine, 0);

        /* The ring must be empty before it is disabled */
        I915_WRITE_CTL(engine, 0);

        return (I915_READ_HEAD(engine) & HEAD_ADDR) == 0;
}

static int init_ring_common(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        struct intel_ring *ring = engine->buffer;
        int ret = 0;

        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

        if (!stop_ring(engine)) {
                /* G45 ring initialization often fails to reset head to zero */
                DRM_DEBUG_DRIVER("%s head not reset to zero "
                                "ctl %08x head %08x tail %08x start %08x\n",
                                engine->name,
                                I915_READ_CTL(engine),
                                I915_READ_HEAD(engine),
                                I915_READ_TAIL(engine),
                                I915_READ_START(engine));

                if (!stop_ring(engine)) {
                        DRM_ERROR("failed to set %s head to zero "
                                  "ctl %08x head %08x tail %08x start %08x\n",
                                  engine->name,
                                  I915_READ_CTL(engine),
                                  I915_READ_HEAD(engine),
                                  I915_READ_TAIL(engine),
                                  I915_READ_START(engine));
                        ret = -EIO;
                        goto out;
                }
        }

        if (HWS_NEEDS_PHYSICAL(dev_priv))
                ring_setup_phys_status_page(engine);
        else
                ring_setup_status_page(engine);

        intel_engine_reset_breadcrumbs(engine);

        /* Enforce ordering by reading HEAD register back */
        I915_READ_HEAD(engine);

        /* Initialize the ring. This must happen _after_ we've cleared the ring
         * registers with the above sequence (the readback of the HEAD registers
         * also enforces ordering), otherwise the hw might lose the new ring
         * register values. */
        I915_WRITE_START(engine, i915_ggtt_offset(ring->vma));

        /* WaClearRingBufHeadRegAtInit:ctg,elk */
        if (I915_READ_HEAD(engine))
                DRM_DEBUG_DRIVER("%s initialization failed [head=%08x], fudging\n",
                                 engine->name, I915_READ_HEAD(engine));

        /* Check that the ring offsets point within the ring! */
        GEM_BUG_ON(!intel_ring_offset_valid(ring, ring->head));
        GEM_BUG_ON(!intel_ring_offset_valid(ring, ring->tail));
        intel_ring_update_space(ring);

        /* First wake the ring up to an empty/idle ring */
        I915_WRITE_HEAD(engine, ring->head);
        I915_WRITE_TAIL(engine, ring->head);
        (void)I915_READ_TAIL(engine);

        I915_WRITE_CTL(engine, RING_CTL_SIZE(ring->size) | RING_VALID);

        /* If the head is still not zero, the ring is dead */
        if (intel_wait_for_register(dev_priv, RING_CTL(engine->mmio_base),
                                    RING_VALID, RING_VALID,
                                    50)) {
                DRM_ERROR("%s initialization failed "
                          "ctl %08x (valid? %d) head %08x [%08x] tail %08x [%08x] start %08x [expected %08x]\n",
                          engine->name,
                          I915_READ_CTL(engine),
                          I915_READ_CTL(engine) & RING_VALID,
                          I915_READ_HEAD(engine), ring->head,
                          I915_READ_TAIL(engine), ring->tail,
                          I915_READ_START(engine),
                          i915_ggtt_offset(ring->vma));
                ret = -EIO;
                goto out;
        }

        if (INTEL_GEN(dev_priv) > 2)
                I915_WRITE_MODE(engine, _MASKED_BIT_DISABLE(STOP_RING));

        /* Now awake, let it get started */
        if (ring->tail != ring->head) {
                I915_WRITE_TAIL(engine, ring->tail);
                (void)I915_READ_TAIL(engine);
        }

        /* Papering over lost _interrupts_ immediately following the restart */
        intel_engine_queue_breadcrumbs(engine);
out:
        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);

        return ret;
}

static void reset_prepare(struct intel_engine_cs *engine)
{
        intel_engine_stop_cs(engine);
}

static void reset_ring(struct intel_engine_cs *engine, bool stalled)
{
        struct i915_timeline *tl = &engine->timeline;
        struct i915_request *pos, *rq;
        unsigned long flags;
        u32 head;

        rq = NULL;
        spin_lock_irqsave(&tl->lock, flags);
        list_for_each_entry(pos, &tl->requests, link) {
                if (!i915_request_completed(pos)) {
                        rq = pos;
                        break;
                }
        }

        GEM_TRACE("%s seqno=%d, current=%d, stalled? %s\n",
                  engine->name,
                  rq ? rq->global_seqno : 0,
                  intel_engine_get_seqno(engine),
                  yesno(stalled));
        /*
         * The guilty request will get skipped on a hung engine.
         *
         * Users of client default contexts do not rely on logical
         * state preserved between batches so it is safe to execute
         * queued requests following the hang. Non default contexts
         * rely on preserved state, so skipping a batch loses the
         * evolution of the state and it needs to be considered corrupted.
         * Executing more queued batches on top of corrupted state is
         * risky. But we take the risk by trying to advance through
         * the queued requests in order to make the client behaviour
         * more predictable around resets, by not throwing away random
         * amount of batches it has prepared for execution. Sophisticated
         * clients can use gem_reset_stats_ioctl and dma fence status
         * (exported via sync_file info ioctl on explicit fences) to observe
         * when it loses the context state and should rebuild accordingly.
         *
         * The context ban, and ultimately the client ban, mechanism are safety
         * valves if client submission ends up resulting in nothing more than
         * subsequent hangs.
         */

        if (rq) {
                /*
                 * Try to restore the logical GPU state to match the
                 * continuation of the request queue. If we skip the
                 * context/PD restore, then the next request may try to execute
                 * assuming that its context is valid and loaded on the GPU and
                 * so may try to access invalid memory, prompting repeated GPU
                 * hangs.
                 *
                 * If the request was guilty, we still restore the logical
                 * state in case the next request requires it (e.g. the
                 * aliasing ppgtt), but skip over the hung batch.
                 *
                 * If the request was innocent, we try to replay the request
                 * with the restored context.
                 */
                i915_reset_request(rq, stalled);

                GEM_BUG_ON(rq->ring != engine->buffer);
                head = rq->head;
        } else {
                head = engine->buffer->tail;
        }
        engine->buffer->head = intel_ring_wrap(engine->buffer, head);

        spin_unlock_irqrestore(&tl->lock, flags);
}

static void reset_finish(struct intel_engine_cs *engine)
{
}

static int intel_rcs_ctx_init(struct i915_request *rq)
{
        int ret;

        ret = intel_engine_emit_ctx_wa(rq);
        if (ret != 0)
                return ret;

        ret = i915_gem_render_state_emit(rq);
        if (ret)
                return ret;

        return 0;
}

static int init_render_ring(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret = init_ring_common(engine);
        if (ret)
                return ret;

        /* WaTimedSingleVertexDispatch:cl,bw,ctg,elk,ilk,snb */
        if (IS_GEN_RANGE(dev_priv, 4, 6))
                I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(VS_TIMER_DISPATCH));

        /* We need to disable the AsyncFlip performance optimisations in order
         * to use MI_WAIT_FOR_EVENT within the CS. It should already be
         * programmed to '1' on all products.
         *
         * WaDisableAsyncFlipPerfMode:snb,ivb,hsw,vlv
         */
        if (IS_GEN_RANGE(dev_priv, 6, 7))
                I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(ASYNC_FLIP_PERF_DISABLE));

        /* Required for the hardware to program scanline values for waiting */
        /* WaEnableFlushTlbInvalidationMode:snb */
        if (IS_GEN(dev_priv, 6))
                I915_WRITE(GFX_MODE,
                           _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_EXPLICIT));

        /* WaBCSVCSTlbInvalidationMode:ivb,vlv,hsw */
        if (IS_GEN(dev_priv, 7))
                I915_WRITE(GFX_MODE_GEN7,
                           _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_EXPLICIT) |
                           _MASKED_BIT_ENABLE(GFX_REPLAY_MODE));

        if (IS_GEN(dev_priv, 6)) {
                /* From the Sandybridge PRM, volume 1 part 3, page 24:
                 * "If this bit is set, STCunit will have LRA as replacement
                 *  policy. [...] This bit must be reset.  LRA replacement
                 *  policy is not supported."
                 */
                I915_WRITE(CACHE_MODE_0,
                           _MASKED_BIT_DISABLE(CM0_STC_EVICT_DISABLE_LRA_SNB));
        }

        if (IS_GEN_RANGE(dev_priv, 6, 7))
                I915_WRITE(INSTPM, _MASKED_BIT_ENABLE(INSTPM_FORCE_ORDERING));

        if (INTEL_GEN(dev_priv) >= 6)
                I915_WRITE_IMR(engine, ~engine->irq_keep_mask);

        return 0;
}

static void cancel_requests(struct intel_engine_cs *engine)
{
        struct i915_request *request;
        unsigned long flags;

        spin_lock_irqsave(&engine->timeline.lock, flags);

        /* Mark all submitted requests as skipped. */
        list_for_each_entry(request, &engine->timeline.requests, link) {
                GEM_BUG_ON(!request->global_seqno);

                if (!i915_request_signaled(request))
                        dma_fence_set_error(&request->fence, -EIO);

                i915_request_mark_complete(request);
        }

        intel_write_status_page(engine,
                                I915_GEM_HWS_INDEX,
                                intel_engine_last_submit(engine));

        /* Remaining _unready_ requests will be nop'ed when submitted */

        spin_unlock_irqrestore(&engine->timeline.lock, flags);
}

static void i9xx_submit_request(struct i915_request *request)
{
        struct drm_i915_private *dev_priv = request->i915;

        i915_request_submit(request);

        I915_WRITE_TAIL(request->engine,
                        intel_ring_set_tail(request->ring, request->tail));
}

static u32 *i9xx_emit_breadcrumb(struct i915_request *rq, u32 *cs)
{
        GEM_BUG_ON(rq->timeline->hwsp_ggtt != rq->engine->status_page.vma);
        GEM_BUG_ON(offset_in_page(rq->timeline->hwsp_offset) != I915_GEM_HWS_SEQNO_ADDR);

        *cs++ = MI_FLUSH;

        *cs++ = MI_STORE_DWORD_INDEX;
        *cs++ = I915_GEM_HWS_SEQNO_ADDR;
        *cs++ = rq->fence.seqno;

        *cs++ = MI_STORE_DWORD_INDEX;
        *cs++ = I915_GEM_HWS_INDEX_ADDR;
        *cs++ = rq->global_seqno;

        *cs++ = MI_USER_INTERRUPT;

        rq->tail = intel_ring_offset(rq, cs);
        assert_ring_tail_valid(rq->ring, rq->tail);

        return cs;
}

#define GEN5_WA_STORES 8 /* must be at least 1! */
static u32 *gen5_emit_breadcrumb(struct i915_request *rq, u32 *cs)
{
        int i;

        GEM_BUG_ON(rq->timeline->hwsp_ggtt != rq->engine->status_page.vma);
        GEM_BUG_ON(offset_in_page(rq->timeline->hwsp_offset) != I915_GEM_HWS_SEQNO_ADDR);

        *cs++ = MI_FLUSH;

        *cs++ = MI_STORE_DWORD_INDEX;
        *cs++ = I915_GEM_HWS_SEQNO_ADDR;
        *cs++ = rq->fence.seqno;

        BUILD_BUG_ON(GEN5_WA_STORES < 1);
        for (i = 0; i < GEN5_WA_STORES; i++) {
                *cs++ = MI_STORE_DWORD_INDEX;
                *cs++ = I915_GEM_HWS_INDEX_ADDR;
                *cs++ = rq->global_seqno;
        }

        *cs++ = MI_USER_INTERRUPT;
        *cs++ = MI_NOOP;

        rq->tail = intel_ring_offset(rq, cs);
        assert_ring_tail_valid(rq->ring, rq->tail);

        return cs;
}
#undef GEN5_WA_STORES

static void
gen5_irq_enable(struct intel_engine_cs *engine)
{
        gen5_enable_gt_irq(engine->i915, engine->irq_enable_mask);
}

static void
gen5_irq_disable(struct intel_engine_cs *engine)
{
        gen5_disable_gt_irq(engine->i915, engine->irq_enable_mask);
}

static void
i9xx_irq_enable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        dev_priv->irq_mask &= ~engine->irq_enable_mask;
        I915_WRITE(IMR, dev_priv->irq_mask);
        POSTING_READ_FW(RING_IMR(engine->mmio_base));
}

static void
i9xx_irq_disable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        dev_priv->irq_mask |= engine->irq_enable_mask;
        I915_WRITE(IMR, dev_priv->irq_mask);
}

static void
i8xx_irq_enable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        dev_priv->irq_mask &= ~engine->irq_enable_mask;
        I915_WRITE16(IMR, dev_priv->irq_mask);
        POSTING_READ16(RING_IMR(engine->mmio_base));
}

static void
i8xx_irq_disable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        dev_priv->irq_mask |= engine->irq_enable_mask;
        I915_WRITE16(IMR, dev_priv->irq_mask);
}

static int
bsd_ring_flush(struct i915_request *rq, u32 mode)
{
        u32 *cs;

        cs = intel_ring_begin(rq, 2);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = MI_FLUSH;
        *cs++ = MI_NOOP;
        intel_ring_advance(rq, cs);
        return 0;
}

static void
gen6_irq_enable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE_IMR(engine,
                       ~(engine->irq_enable_mask |
                         engine->irq_keep_mask));

        /* Flush/delay to ensure the RING_IMR is active before the GT IMR */
        POSTING_READ_FW(RING_IMR(engine->mmio_base));

        gen5_enable_gt_irq(dev_priv, engine->irq_enable_mask);
}

static void
gen6_irq_disable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE_IMR(engine, ~engine->irq_keep_mask);
        gen5_disable_gt_irq(dev_priv, engine->irq_enable_mask);
}

static void
hsw_vebox_irq_enable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE_IMR(engine, ~engine->irq_enable_mask);

        /* Flush/delay to ensure the RING_IMR is active before the GT IMR */
        POSTING_READ_FW(RING_IMR(engine->mmio_base));

        gen6_unmask_pm_irq(dev_priv, engine->irq_enable_mask);
}

static void
hsw_vebox_irq_disable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE_IMR(engine, ~0);
        gen6_mask_pm_irq(dev_priv, engine->irq_enable_mask);
}

static int
i965_emit_bb_start(struct i915_request *rq,
                   u64 offset, u32 length,
                   unsigned int dispatch_flags)
{
        u32 *cs;

        cs = intel_ring_begin(rq, 2);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = MI_BATCH_BUFFER_START | MI_BATCH_GTT | (dispatch_flags &
                I915_DISPATCH_SECURE ? 0 : MI_BATCH_NON_SECURE_I965);
        *cs++ = offset;
        intel_ring_advance(rq, cs);

        return 0;
}

/* Just userspace ABI convention to limit the wa batch bo to a resonable size */
#define I830_BATCH_LIMIT SZ_256K
#define I830_TLB_ENTRIES (2)
#define I830_WA_SIZE max(I830_TLB_ENTRIES*4096, I830_BATCH_LIMIT)
static int
i830_emit_bb_start(struct i915_request *rq,
                   u64 offset, u32 len,
                   unsigned int dispatch_flags)
{
        u32 *cs, cs_offset = i915_scratch_offset(rq->i915);

        GEM_BUG_ON(rq->i915->gt.scratch->size < I830_WA_SIZE);

        cs = intel_ring_begin(rq, 6);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        /* Evict the invalid PTE TLBs */
        *cs++ = COLOR_BLT_CMD | BLT_WRITE_RGBA;
        *cs++ = BLT_DEPTH_32 | BLT_ROP_COLOR_COPY | 4096;
        *cs++ = I830_TLB_ENTRIES << 16 | 4; /* load each page */
        *cs++ = cs_offset;
        *cs++ = 0xdeadbeef;
        *cs++ = MI_NOOP;
        intel_ring_advance(rq, cs);

        if ((dispatch_flags & I915_DISPATCH_PINNED) == 0) {
                if (len > I830_BATCH_LIMIT)
                        return -ENOSPC;

                cs = intel_ring_begin(rq, 6 + 2);
                if (IS_ERR(cs))
                        return PTR_ERR(cs);

                /* Blit the batch (which has now all relocs applied) to the
                 * stable batch scratch bo area (so that the CS never
                 * stumbles over its tlb invalidation bug) ...
                 */
                *cs++ = SRC_COPY_BLT_CMD | BLT_WRITE_RGBA;
                *cs++ = BLT_DEPTH_32 | BLT_ROP_SRC_COPY | 4096;
                *cs++ = DIV_ROUND_UP(len, 4096) << 16 | 4096;
                *cs++ = cs_offset;
                *cs++ = 4096;
                *cs++ = offset;

                *cs++ = MI_FLUSH;
                *cs++ = MI_NOOP;
                intel_ring_advance(rq, cs);

                /* ... and execute it. */
                offset = cs_offset;
        }

        cs = intel_ring_begin(rq, 2);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = MI_BATCH_BUFFER_START | MI_BATCH_GTT;
        *cs++ = offset | (dispatch_flags & I915_DISPATCH_SECURE ? 0 :
                MI_BATCH_NON_SECURE);
        intel_ring_advance(rq, cs);

        return 0;
}

static int
i915_emit_bb_start(struct i915_request *rq,
                   u64 offset, u32 len,
                   unsigned int dispatch_flags)
{
        u32 *cs;

        cs = intel_ring_begin(rq, 2);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = MI_BATCH_BUFFER_START | MI_BATCH_GTT;
        *cs++ = offset | (dispatch_flags & I915_DISPATCH_SECURE ? 0 :
                MI_BATCH_NON_SECURE);
        intel_ring_advance(rq, cs);

        return 0;
}

int intel_ring_pin(struct intel_ring *ring)
{
        struct i915_vma *vma = ring->vma;
        enum i915_map_type map = i915_coherent_map_type(vma->vm->i915);
        unsigned int flags;
        void *addr;
        int ret;

        GEM_BUG_ON(ring->vaddr);

        ret = i915_timeline_pin(ring->timeline);
        if (ret)
                return ret;

        flags = PIN_GLOBAL;

        /* Ring wraparound at offset 0 sometimes hangs. No idea why. */
        flags |= PIN_OFFSET_BIAS | i915_ggtt_pin_bias(vma);

        if (vma->obj->stolen)
                flags |= PIN_MAPPABLE;
        else
                flags |= PIN_HIGH;

        if (!(vma->flags & I915_VMA_GLOBAL_BIND)) {
                if (flags & PIN_MAPPABLE || map == I915_MAP_WC)
                        ret = i915_gem_object_set_to_gtt_domain(vma->obj, true);
                else
                        ret = i915_gem_object_set_to_cpu_domain(vma->obj, true);
                if (unlikely(ret))
                        goto unpin_timeline;
        }

        ret = i915_vma_pin(vma, 0, 0, flags);
        if (unlikely(ret))
                goto unpin_timeline;

        if (i915_vma_is_map_and_fenceable(vma))
                addr = (void __force *)i915_vma_pin_iomap(vma);
        else
                addr = i915_gem_object_pin_map(vma->obj, map);
        if (IS_ERR(addr)) {
                ret = PTR_ERR(addr);
                goto unpin_ring;
        }

        vma->obj->pin_global++;

        ring->vaddr = addr;
        return 0;

unpin_ring:
        i915_vma_unpin(vma);
unpin_timeline:
        i915_timeline_unpin(ring->timeline);
        return ret;
}

void intel_ring_reset(struct intel_ring *ring, u32 tail)
{
        GEM_BUG_ON(!intel_ring_offset_valid(ring, tail));

        ring->tail = tail;
        ring->head = tail;
        ring->emit = tail;
        intel_ring_update_space(ring);
}

void intel_ring_unpin(struct intel_ring *ring)
{
        GEM_BUG_ON(!ring->vma);
        GEM_BUG_ON(!ring->vaddr);

        /* Discard any unused bytes beyond that submitted to hw. */
        intel_ring_reset(ring, ring->tail);

        if (i915_vma_is_map_and_fenceable(ring->vma))
                i915_vma_unpin_iomap(ring->vma);
        else
                i915_gem_object_unpin_map(ring->vma->obj);
        ring->vaddr = NULL;

        ring->vma->obj->pin_global--;
        i915_vma_unpin(ring->vma);

        i915_timeline_unpin(ring->timeline);
}

static struct i915_vma *
intel_ring_create_vma(struct drm_i915_private *dev_priv, int size)
{
        struct i915_address_space *vm = &dev_priv->ggtt.vm;
        struct drm_i915_gem_object *obj;
        struct i915_vma *vma;

        obj = i915_gem_object_create_stolen(dev_priv, size);
        if (!obj)
                obj = i915_gem_object_create_internal(dev_priv, size);
        if (IS_ERR(obj))
                return ERR_CAST(obj);

        /*
         * Mark ring buffers as read-only from GPU side (so no stray overwrites)
         * if supported by the platform's GGTT.
         */
        if (vm->has_read_only)
                i915_gem_object_set_readonly(obj);

        vma = i915_vma_instance(obj, vm, NULL);
        if (IS_ERR(vma))
                goto err;

        return vma;

err:
        i915_gem_object_put(obj);
        return vma;
}

struct intel_ring *
intel_engine_create_ring(struct intel_engine_cs *engine,
                         struct i915_timeline *timeline,
                         int size)
{
        struct intel_ring *ring;
        struct i915_vma *vma;

        GEM_BUG_ON(!is_power_of_2(size));
        GEM_BUG_ON(RING_CTL_SIZE(size) & ~RING_NR_PAGES);
        GEM_BUG_ON(timeline == &engine->timeline);
        lockdep_assert_held(&engine->i915->drm.struct_mutex);

        ring = kzalloc(sizeof(*ring), GFP_KERNEL);
        if (!ring)
                return ERR_PTR(-ENOMEM);

        INIT_LIST_HEAD(&ring->request_list);
        ring->timeline = i915_timeline_get(timeline);

        ring->size = size;
        /* Workaround an erratum on the i830 which causes a hang if
         * the TAIL pointer points to within the last 2 cachelines
         * of the buffer.
         */
        ring->effective_size = size;
        if (IS_I830(engine->i915) || IS_I845G(engine->i915))
                ring->effective_size -= 2 * CACHELINE_BYTES;

        intel_ring_update_space(ring);

        vma = intel_ring_create_vma(engine->i915, size);
        if (IS_ERR(vma)) {
                kfree(ring);
                return ERR_CAST(vma);
        }
        ring->vma = vma;

        return ring;
}

void
intel_ring_free(struct intel_ring *ring)
{
        struct drm_i915_gem_object *obj = ring->vma->obj;

        i915_vma_close(ring->vma);
        __i915_gem_object_release_unless_active(obj);

        i915_timeline_put(ring->timeline);
        kfree(ring);
}

static void intel_ring_context_destroy(struct intel_context *ce)
{
        GEM_BUG_ON(ce->pin_count);

        if (!ce->state)
                return;

        GEM_BUG_ON(i915_gem_object_is_active(ce->state->obj));
        i915_gem_object_put(ce->state->obj);
}

static int __context_pin_ppgtt(struct i915_gem_context *ctx)
{
        struct i915_hw_ppgtt *ppgtt;
        int err = 0;

        ppgtt = ctx->ppgtt ?: ctx->i915->mm.aliasing_ppgtt;
        if (ppgtt)
                err = gen6_ppgtt_pin(ppgtt);

        return err;
}

static void __context_unpin_ppgtt(struct i915_gem_context *ctx)
{
        struct i915_hw_ppgtt *ppgtt;

        ppgtt = ctx->ppgtt ?: ctx->i915->mm.aliasing_ppgtt;
        if (ppgtt)
                gen6_ppgtt_unpin(ppgtt);
}

static int __context_pin(struct intel_context *ce)
{
        struct i915_vma *vma;
        int err;

        vma = ce->state;
        if (!vma)
                return 0;

        /*
         * Clear this page out of any CPU caches for coherent swap-in/out.
         * We only want to do this on the first bind so that we do not stall
         * on an active context (which by nature is already on the GPU).
         */
        if (!(vma->flags & I915_VMA_GLOBAL_BIND)) {
                err = i915_gem_object_set_to_gtt_domain(vma->obj, true);
                if (err)
                        return err;
        }

        err = i915_vma_pin(vma, 0, 0, PIN_GLOBAL | PIN_HIGH);
        if (err)
                return err;

        /*
         * And mark is as a globally pinned object to let the shrinker know
         * it cannot reclaim the object until we release it.
         */
        vma->obj->pin_global++;

        return 0;
}

static void __context_unpin(struct intel_context *ce)
{
        struct i915_vma *vma;

        vma = ce->state;
        if (!vma)
                return;

        vma->obj->pin_global--;
        i915_vma_unpin(vma);
}

static void intel_ring_context_unpin(struct intel_context *ce)
{
        __context_unpin_ppgtt(ce->gem_context);
        __context_unpin(ce);

        i915_gem_context_put(ce->gem_context);
}

static struct i915_vma *
alloc_context_vma(struct intel_engine_cs *engine)
{
        struct drm_i915_private *i915 = engine->i915;
        struct drm_i915_gem_object *obj;
        struct i915_vma *vma;
        int err;

        obj = i915_gem_object_create(i915, engine->context_size);
        if (IS_ERR(obj))
                return ERR_CAST(obj);

        if (engine->default_state) {
                void *defaults, *vaddr;

                vaddr = i915_gem_object_pin_map(obj, I915_MAP_WB);
                if (IS_ERR(vaddr)) {
                        err = PTR_ERR(vaddr);
                        goto err_obj;
                }

                defaults = i915_gem_object_pin_map(engine->default_state,
                                                   I915_MAP_WB);
                if (IS_ERR(defaults)) {
                        err = PTR_ERR(defaults);
                        goto err_map;
                }

                memcpy(vaddr, defaults, engine->context_size);

                i915_gem_object_unpin_map(engine->default_state);
                i915_gem_object_unpin_map(obj);
        }

        /*
         * Try to make the context utilize L3 as well as LLC.
         *
         * On VLV we don't have L3 controls in the PTEs so we
         * shouldn't touch the cache level, especially as that
         * would make the object snooped which might have a
         * negative performance impact.
         *
         * Snooping is required on non-llc platforms in execlist
         * mode, but since all GGTT accesses use PAT entry 0 we
         * get snooping anyway regardless of cache_level.
         *
         * This is only applicable for Ivy Bridge devices since
         * later platforms don't have L3 control bits in the PTE.
         */
        if (IS_IVYBRIDGE(i915)) {
                /* Ignore any error, regard it as a simple optimisation */
                i915_gem_object_set_cache_level(obj, I915_CACHE_L3_LLC);
        }

        vma = i915_vma_instance(obj, &i915->ggtt.vm, NULL);
        if (IS_ERR(vma)) {
                err = PTR_ERR(vma);
                goto err_obj;
        }

        return vma;

err_map:
        i915_gem_object_unpin_map(obj);
err_obj:
        i915_gem_object_put(obj);
        return ERR_PTR(err);
}

static struct intel_context *
__ring_context_pin(struct intel_engine_cs *engine,
                   struct i915_gem_context *ctx,
                   struct intel_context *ce)
{
        int err;

        if (!ce->state && engine->context_size) {
                struct i915_vma *vma;

                vma = alloc_context_vma(engine);
                if (IS_ERR(vma)) {
                        err = PTR_ERR(vma);
                        goto err;
                }

                ce->state = vma;
        }

        err = __context_pin(ce);
        if (err)
                goto err;

        err = __context_pin_ppgtt(ce->gem_context);
        if (err)
                goto err_unpin;

        i915_gem_context_get(ctx);

        /* One ringbuffer to rule them all */
        GEM_BUG_ON(!engine->buffer);
        ce->ring = engine->buffer;

        return ce;

err_unpin:
        __context_unpin(ce);
err:
        ce->pin_count = 0;
        return ERR_PTR(err);
}

static const struct intel_context_ops ring_context_ops = {
        .unpin = intel_ring_context_unpin,
        .destroy = intel_ring_context_destroy,
};

static struct intel_context *
intel_ring_context_pin(struct intel_engine_cs *engine,
                       struct i915_gem_context *ctx)
{
        struct intel_context *ce = to_intel_context(ctx, engine);

        lockdep_assert_held(&ctx->i915->drm.struct_mutex);

        if (likely(ce->pin_count++))
                return ce;
        GEM_BUG_ON(!ce->pin_count); /* no overflow please! */

        ce->ops = &ring_context_ops;

        return __ring_context_pin(engine, ctx, ce);
}

static int intel_init_ring_buffer(struct intel_engine_cs *engine)
{
        struct i915_timeline *timeline;
        struct intel_ring *ring;
        int err;

        err = intel_engine_setup_common(engine);
        if (err)
                return err;

        timeline = i915_timeline_create(engine->i915,
                                        engine->name,
                                        engine->status_page.vma);
        if (IS_ERR(timeline)) {
                err = PTR_ERR(timeline);
                goto err;
        }
        GEM_BUG_ON(timeline->has_initial_breadcrumb);

        ring = intel_engine_create_ring(engine, timeline, 32 * PAGE_SIZE);
        i915_timeline_put(timeline);
        if (IS_ERR(ring)) {
                err = PTR_ERR(ring);
                goto err;
        }

        err = intel_ring_pin(ring);
        if (err)
                goto err_ring;

        GEM_BUG_ON(engine->buffer);
        engine->buffer = ring;

        err = intel_engine_init_common(engine);
        if (err)
                goto err_unpin;

        GEM_BUG_ON(ring->timeline->hwsp_ggtt != engine->status_page.vma);

        return 0;

err_unpin:
        intel_ring_unpin(ring);
err_ring:
        intel_ring_free(ring);
err:
        intel_engine_cleanup_common(engine);
        return err;
}

void intel_engine_cleanup(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        WARN_ON(INTEL_GEN(dev_priv) > 2 &&
                (I915_READ_MODE(engine) & MODE_IDLE) == 0);

        intel_ring_unpin(engine->buffer);
        intel_ring_free(engine->buffer);

        if (engine->cleanup)
                engine->cleanup(engine);

        intel_engine_cleanup_common(engine);

        dev_priv->engine[engine->id] = NULL;
        kfree(engine);
}

void intel_legacy_submission_resume(struct drm_i915_private *dev_priv)
{
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        /* Restart from the beginning of the rings for convenience */
        for_each_engine(engine, dev_priv, id)
                intel_ring_reset(engine->buffer, 0);
}

static int load_pd_dir(struct i915_request *rq,
                       const struct i915_hw_ppgtt *ppgtt)
{
        const struct intel_engine_cs * const engine = rq->engine;
        u32 *cs;

        cs = intel_ring_begin(rq, 6);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = MI_LOAD_REGISTER_IMM(1);
        *cs++ = i915_mmio_reg_offset(RING_PP_DIR_DCLV(engine));
        *cs++ = PP_DIR_DCLV_2G;

        *cs++ = MI_LOAD_REGISTER_IMM(1);
        *cs++ = i915_mmio_reg_offset(RING_PP_DIR_BASE(engine));
        *cs++ = ppgtt->pd.base.ggtt_offset << 10;

        intel_ring_advance(rq, cs);

        return 0;
}

static int flush_pd_dir(struct i915_request *rq)
{
        const struct intel_engine_cs * const engine = rq->engine;
        u32 *cs;

        cs = intel_ring_begin(rq, 4);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        /* Stall until the page table load is complete */
        *cs++ = MI_STORE_REGISTER_MEM | MI_SRM_LRM_GLOBAL_GTT;
        *cs++ = i915_mmio_reg_offset(RING_PP_DIR_BASE(engine));
        *cs++ = i915_scratch_offset(rq->i915);
        *cs++ = MI_NOOP;

        intel_ring_advance(rq, cs);
        return 0;
}

static inline int mi_set_context(struct i915_request *rq, u32 flags)
{
        struct drm_i915_private *i915 = rq->i915;
        struct intel_engine_cs *engine = rq->engine;
        enum intel_engine_id id;
        const int num_rings =
                IS_HSW_GT1(i915) ? RUNTIME_INFO(i915)->num_rings - 1 : 0;
        bool force_restore = false;
        int len;
        u32 *cs;

        flags |= MI_MM_SPACE_GTT;
        if (IS_HASWELL(i915))
                /* These flags are for resource streamer on HSW+ */
                flags |= HSW_MI_RS_SAVE_STATE_EN | HSW_MI_RS_RESTORE_STATE_EN;
        else
                flags |= MI_SAVE_EXT_STATE_EN | MI_RESTORE_EXT_STATE_EN;

        len = 4;
        if (IS_GEN(i915, 7))
                len += 2 + (num_rings ? 4*num_rings + 6 : 0);
        if (flags & MI_FORCE_RESTORE) {
                GEM_BUG_ON(flags & MI_RESTORE_INHIBIT);
                flags &= ~MI_FORCE_RESTORE;
                force_restore = true;
                len += 2;
        }

        cs = intel_ring_begin(rq, len);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        /* WaProgramMiArbOnOffAroundMiSetContext:ivb,vlv,hsw,bdw,chv */
        if (IS_GEN(i915, 7)) {
                *cs++ = MI_ARB_ON_OFF | MI_ARB_DISABLE;
                if (num_rings) {
                        struct intel_engine_cs *signaller;

                        *cs++ = MI_LOAD_REGISTER_IMM(num_rings);
                        for_each_engine(signaller, i915, id) {
                                if (signaller == engine)
                                        continue;

                                *cs++ = i915_mmio_reg_offset(
                                           RING_PSMI_CTL(signaller->mmio_base));
                                *cs++ = _MASKED_BIT_ENABLE(
                                                GEN6_PSMI_SLEEP_MSG_DISABLE);
                        }
                }
        }

        if (force_restore) {
                /*
                 * The HW doesn't handle being told to restore the current
                 * context very well. Quite often it likes goes to go off and
                 * sulk, especially when it is meant to be reloading PP_DIR.
                 * A very simple fix to force the reload is to simply switch
                 * away from the current context and back again.
                 *
                 * Note that the kernel_context will contain random state
                 * following the INHIBIT_RESTORE. We accept this since we
                 * never use the kernel_context state; it is merely a
                 * placeholder we use to flush other contexts.
                 */
                *cs++ = MI_SET_CONTEXT;
                *cs++ = i915_ggtt_offset(to_intel_context(i915->kernel_context,
                                                          engine)->state) |
                        MI_MM_SPACE_GTT |
                        MI_RESTORE_INHIBIT;
        }

        *cs++ = MI_NOOP;
        *cs++ = MI_SET_CONTEXT;
        *cs++ = i915_ggtt_offset(rq->hw_context->state) | flags;
        /*
         * w/a: MI_SET_CONTEXT must always be followed by MI_NOOP
         * WaMiSetContext_Hang:snb,ivb,vlv
         */
        *cs++ = MI_NOOP;

        if (IS_GEN(i915, 7)) {
                if (num_rings) {
                        struct intel_engine_cs *signaller;
                        i915_reg_t last_reg = {}; /* keep gcc quiet */

                        *cs++ = MI_LOAD_REGISTER_IMM(num_rings);
                        for_each_engine(signaller, i915, id) {
                                if (signaller == engine)
                                        continue;

                                last_reg = RING_PSMI_CTL(signaller->mmio_base);
                                *cs++ = i915_mmio_reg_offset(last_reg);
                                *cs++ = _MASKED_BIT_DISABLE(
                                                GEN6_PSMI_SLEEP_MSG_DISABLE);
                        }

                        /* Insert a delay before the next switch! */
                        *cs++ = MI_STORE_REGISTER_MEM | MI_SRM_LRM_GLOBAL_GTT;
                        *cs++ = i915_mmio_reg_offset(last_reg);
                        *cs++ = i915_scratch_offset(rq->i915);
                        *cs++ = MI_NOOP;
                }
                *cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE;
        }

        intel_ring_advance(rq, cs);

        return 0;
}

static int remap_l3(struct i915_request *rq, int slice)
{
        u32 *cs, *remap_info = rq->i915->l3_parity.remap_info[slice];
        int i;

        if (!remap_info)
                return 0;

        cs = intel_ring_begin(rq, GEN7_L3LOG_SIZE/4 * 2 + 2);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        /*
         * Note: We do not worry about the concurrent register cacheline hang
         * here because no other code should access these registers other than
         * at initialization time.
         */
        *cs++ = MI_LOAD_REGISTER_IMM(GEN7_L3LOG_SIZE/4);
        for (i = 0; i < GEN7_L3LOG_SIZE/4; i++) {
                *cs++ = i915_mmio_reg_offset(GEN7_L3LOG(slice, i));
                *cs++ = remap_info[i];
        }
        *cs++ = MI_NOOP;
        intel_ring_advance(rq, cs);

        return 0;
}

static int switch_context(struct i915_request *rq)
{
        struct intel_engine_cs *engine = rq->engine;
        struct i915_gem_context *ctx = rq->gem_context;
        struct i915_hw_ppgtt *ppgtt = ctx->ppgtt ?: rq->i915->mm.aliasing_ppgtt;
        unsigned int unwind_mm = 0;
        u32 hw_flags = 0;
        int ret, i;

        lockdep_assert_held(&rq->i915->drm.struct_mutex);
        GEM_BUG_ON(HAS_EXECLISTS(rq->i915));

        if (ppgtt) {
                int loops;

                /*
                 * Baytail takes a little more convincing that it really needs
                 * to reload the PD between contexts. It is not just a little
                 * longer, as adding more stalls after the load_pd_dir (i.e.
                 * adding a long loop around flush_pd_dir) is not as effective
                 * as reloading the PD umpteen times. 32 is derived from
                 * experimentation (gem_exec_parallel/fds) and has no good
                 * explanation.
                 */
                loops = 1;
                if (engine->id == BCS && IS_VALLEYVIEW(engine->i915))
                        loops = 32;

                do {
                        ret = load_pd_dir(rq, ppgtt);
                        if (ret)
                                goto err;
                } while (--loops);

                if (intel_engine_flag(engine) & ppgtt->pd_dirty_rings) {
                        unwind_mm = intel_engine_flag(engine);
                        ppgtt->pd_dirty_rings &= ~unwind_mm;
                        hw_flags = MI_FORCE_RESTORE;
                }
        }

        if (rq->hw_context->state) {
                GEM_BUG_ON(engine->id != RCS);

                /*
                 * The kernel context(s) is treated as pure scratch and is not
                 * expected to retain any state (as we sacrifice it during
                 * suspend and on resume it may be corrupted). This is ok,
                 * as nothing actually executes using the kernel context; it
                 * is purely used for flushing user contexts.
                 */
                if (i915_gem_context_is_kernel(ctx))
                        hw_flags = MI_RESTORE_INHIBIT;

                ret = mi_set_context(rq, hw_flags);
                if (ret)
                        goto err_mm;
        }

        if (ppgtt) {
                ret = engine->emit_flush(rq, EMIT_INVALIDATE);
                if (ret)
                        goto err_mm;

                ret = flush_pd_dir(rq);
                if (ret)
                        goto err_mm;

                /*
                 * Not only do we need a full barrier (post-sync write) after
                 * invalidating the TLBs, but we need to wait a little bit
                 * longer. Whether this is merely delaying us, or the
                 * subsequent flush is a key part of serialising with the
                 * post-sync op, this extra pass appears vital before a
                 * mm switch!
                 */
                ret = engine->emit_flush(rq, EMIT_INVALIDATE);
                if (ret)
                        goto err_mm;

                ret = engine->emit_flush(rq, EMIT_FLUSH);
                if (ret)
                        goto err_mm;
        }

        if (ctx->remap_slice) {
                for (i = 0; i < MAX_L3_SLICES; i++) {
                        if (!(ctx->remap_slice & BIT(i)))
                                continue;

                        ret = remap_l3(rq, i);
                        if (ret)
                                goto err_mm;
                }

                ctx->remap_slice = 0;
        }

        return 0;

err_mm:
        if (unwind_mm)
                ppgtt->pd_dirty_rings |= unwind_mm;
err:
        return ret;
}

static int ring_request_alloc(struct i915_request *request)
{
        int ret;

        GEM_BUG_ON(!request->hw_context->pin_count);
        GEM_BUG_ON(request->timeline->has_initial_breadcrumb);

        /*
         * Flush enough space to reduce the likelihood of waiting after
         * we start building the request - in which case we will just
         * have to repeat work.
         */
        request->reserved_space += LEGACY_REQUEST_SIZE;

        ret = switch_context(request);
        if (ret)
                return ret;

        /* Unconditionally invalidate GPU caches and TLBs. */
        ret = request->engine->emit_flush(request, EMIT_INVALIDATE);
        if (ret)
                return ret;

        request->reserved_space -= LEGACY_REQUEST_SIZE;
        return 0;
}

static noinline int wait_for_space(struct intel_ring *ring, unsigned int bytes)
{
        struct i915_request *target;
        long timeout;

        lockdep_assert_held(&ring->vma->vm->i915->drm.struct_mutex);

        if (intel_ring_update_space(ring) >= bytes)
                return 0;

        GEM_BUG_ON(list_empty(&ring->request_list));
        list_for_each_entry(target, &ring->request_list, ring_link) {
                /* Would completion of this request free enough space? */
                if (bytes <= __intel_ring_space(target->postfix,
                                                ring->emit, ring->size))
                        break;
        }

        if (WARN_ON(&target->ring_link == &ring->request_list))
                return -ENOSPC;

        timeout = i915_request_wait(target,
                                    I915_WAIT_INTERRUPTIBLE | I915_WAIT_LOCKED,
                                    MAX_SCHEDULE_TIMEOUT);
        if (timeout < 0)
                return timeout;

        i915_request_retire_upto(target);

        intel_ring_update_space(ring);
        GEM_BUG_ON(ring->space < bytes);
        return 0;
}

u32 *intel_ring_begin(struct i915_request *rq, unsigned int num_dwords)
{
        struct intel_ring *ring = rq->ring;
        const unsigned int remain_usable = ring->effective_size - ring->emit;
        const unsigned int bytes = num_dwords * sizeof(u32);
        unsigned int need_wrap = 0;
        unsigned int total_bytes;
        u32 *cs;

        /* Packets must be qword aligned. */
        GEM_BUG_ON(num_dwords & 1);

        total_bytes = bytes + rq->reserved_space;
        GEM_BUG_ON(total_bytes > ring->effective_size);

        if (unlikely(total_bytes > remain_usable)) {
                const int remain_actual = ring->size - ring->emit;

                if (bytes > remain_usable) {
                        /*
                         * Not enough space for the basic request. So need to
                         * flush out the remainder and then wait for
                         * base + reserved.
                         */
                        total_bytes += remain_actual;
                        need_wrap = remain_actual | 1;
                } else  {
                        /*
                         * The base request will fit but the reserved space
                         * falls off the end. So we don't need an immediate
                         * wrap and only need to effectively wait for the
                         * reserved size from the start of ringbuffer.
                         */
                        total_bytes = rq->reserved_space + remain_actual;
                }
        }

        if (unlikely(total_bytes > ring->space)) {
                int ret;

                /*
                 * Space is reserved in the ringbuffer for finalising the
                 * request, as that cannot be allowed to fail. During request
                 * finalisation, reserved_space is set to 0 to stop the
                 * overallocation and the assumption is that then we never need
                 * to wait (which has the risk of failing with EINTR).
                 *
                 * See also i915_request_alloc() and i915_request_add().
                 */
                GEM_BUG_ON(!rq->reserved_space);

                ret = wait_for_space(ring, total_bytes);
                if (unlikely(ret))
                        return ERR_PTR(ret);
        }

        if (unlikely(need_wrap)) {
                need_wrap &= ~1;
                GEM_BUG_ON(need_wrap > ring->space);
                GEM_BUG_ON(ring->emit + need_wrap > ring->size);
                GEM_BUG_ON(!IS_ALIGNED(need_wrap, sizeof(u64)));

                /* Fill the tail with MI_NOOP */
                memset64(ring->vaddr + ring->emit, 0, need_wrap / sizeof(u64));
                ring->space -= need_wrap;
                ring->emit = 0;
        }

        GEM_BUG_ON(ring->emit > ring->size - bytes);
        GEM_BUG_ON(ring->space < bytes);
        cs = ring->vaddr + ring->emit;
        GEM_DEBUG_EXEC(memset32(cs, POISON_INUSE, bytes / sizeof(*cs)));
        ring->emit += bytes;
        ring->space -= bytes;

        return cs;
}

/* Align the ring tail to a cacheline boundary */
int intel_ring_cacheline_align(struct i915_request *rq)
{
        int num_dwords;
        void *cs;

        num_dwords = (rq->ring->emit & (CACHELINE_BYTES - 1)) / sizeof(u32);
        if (num_dwords == 0)
                return 0;

        num_dwords = CACHELINE_DWORDS - num_dwords;
        GEM_BUG_ON(num_dwords & 1);

        cs = intel_ring_begin(rq, num_dwords);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        memset64(cs, (u64)MI_NOOP << 32 | MI_NOOP, num_dwords / 2);
        intel_ring_advance(rq, cs);

        GEM_BUG_ON(rq->ring->emit & (CACHELINE_BYTES - 1));
        return 0;
}

static void gen6_bsd_submit_request(struct i915_request *request)
{
        struct drm_i915_private *dev_priv = request->i915;

        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

       /* Every tail move must follow the sequence below */

        /* Disable notification that the ring is IDLE. The GT
         * will then assume that it is busy and bring it out of rc6.
         */
        I915_WRITE_FW(GEN6_BSD_SLEEP_PSMI_CONTROL,
                      _MASKED_BIT_ENABLE(GEN6_BSD_SLEEP_MSG_DISABLE));

        /* Clear the context id. Here be magic! */
        I915_WRITE64_FW(GEN6_BSD_RNCID, 0x0);

        /* Wait for the ring not to be idle, i.e. for it to wake up. */
        if (__intel_wait_for_register_fw(dev_priv,
                                         GEN6_BSD_SLEEP_PSMI_CONTROL,
                                         GEN6_BSD_SLEEP_INDICATOR,
                                         0,
                                         1000, 0, NULL))
                DRM_ERROR("timed out waiting for the BSD ring to wake up\n");

        /* Now that the ring is fully powered up, update the tail */
        i9xx_submit_request(request);

        /* Let the ring send IDLE messages to the GT again,
         * and so let it sleep to conserve power when idle.
         */
        I915_WRITE_FW(GEN6_BSD_SLEEP_PSMI_CONTROL,
                      _MASKED_BIT_DISABLE(GEN6_BSD_SLEEP_MSG_DISABLE));

        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
}

static int mi_flush_dw(struct i915_request *rq, u32 flags)
{
        u32 cmd, *cs;

        cs = intel_ring_begin(rq, 4);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        cmd = MI_FLUSH_DW;

        /*
         * We always require a command barrier so that subsequent
         * commands, such as breadcrumb interrupts, are strictly ordered
         * wrt the contents of the write cache being flushed to memory
         * (and thus being coherent from the CPU).
         */
        cmd |= MI_FLUSH_DW_STORE_INDEX | MI_FLUSH_DW_OP_STOREDW;

        /*
         * Bspec vol 1c.3 - blitter engine command streamer:
         * "If ENABLED, all TLBs will be invalidated once the flush
         * operation is complete. This bit is only valid when the
         * Post-Sync Operation field is a value of 1h or 3h."
         */
        cmd |= flags;

        *cs++ = cmd;
        *cs++ = I915_GEM_HWS_SCRATCH_ADDR | MI_FLUSH_DW_USE_GTT;
        *cs++ = 0;
        *cs++ = MI_NOOP;

        intel_ring_advance(rq, cs);

        return 0;
}

static int gen6_flush_dw(struct i915_request *rq, u32 mode, u32 invflags)
{
        return mi_flush_dw(rq, mode & EMIT_INVALIDATE ? invflags : 0);
}

static int gen6_bsd_ring_flush(struct i915_request *rq, u32 mode)
{
        return gen6_flush_dw(rq, mode, MI_INVALIDATE_TLB | MI_INVALIDATE_BSD);
}

static int
hsw_emit_bb_start(struct i915_request *rq,
                  u64 offset, u32 len,
                  unsigned int dispatch_flags)
{
        u32 *cs;

        cs = intel_ring_begin(rq, 2);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = MI_BATCH_BUFFER_START | (dispatch_flags & I915_DISPATCH_SECURE ?
                0 : MI_BATCH_PPGTT_HSW | MI_BATCH_NON_SECURE_HSW);
        /* bit0-7 is the length on GEN6+ */
        *cs++ = offset;
        intel_ring_advance(rq, cs);

        return 0;
}

static int
gen6_emit_bb_start(struct i915_request *rq,
                   u64 offset, u32 len,
                   unsigned int dispatch_flags)
{
        u32 *cs;

        cs = intel_ring_begin(rq, 2);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = MI_BATCH_BUFFER_START | (dispatch_flags & I915_DISPATCH_SECURE ?
                0 : MI_BATCH_NON_SECURE_I965);
        /* bit0-7 is the length on GEN6+ */
        *cs++ = offset;
        intel_ring_advance(rq, cs);

        return 0;
}

/* Blitter support (SandyBridge+) */

static int gen6_ring_flush(struct i915_request *rq, u32 mode)
{
        return gen6_flush_dw(rq, mode, MI_INVALIDATE_TLB);
}

static void intel_ring_init_irq(struct drm_i915_private *dev_priv,
                                struct intel_engine_cs *engine)
{
        if (INTEL_GEN(dev_priv) >= 6) {
                engine->irq_enable = gen6_irq_enable;
                engine->irq_disable = gen6_irq_disable;
        } else if (INTEL_GEN(dev_priv) >= 5) {
                engine->irq_enable = gen5_irq_enable;
                engine->irq_disable = gen5_irq_disable;
        } else if (INTEL_GEN(dev_priv) >= 3) {
                engine->irq_enable = i9xx_irq_enable;
                engine->irq_disable = i9xx_irq_disable;
        } else {
                engine->irq_enable = i8xx_irq_enable;
                engine->irq_disable = i8xx_irq_disable;
        }
}

static void i9xx_set_default_submission(struct intel_engine_cs *engine)
{
        engine->submit_request = i9xx_submit_request;
        engine->cancel_requests = cancel_requests;

        engine->park = NULL;
        engine->unpark = NULL;
}

static void gen6_bsd_set_default_submission(struct intel_engine_cs *engine)
{
        i9xx_set_default_submission(engine);
        engine->submit_request = gen6_bsd_submit_request;
}

static void intel_ring_default_vfuncs(struct drm_i915_private *dev_priv,
                                      struct intel_engine_cs *engine)
{
        /* gen8+ are only supported with execlists */
        GEM_BUG_ON(INTEL_GEN(dev_priv) >= 8);

        intel_ring_init_irq(dev_priv, engine);

        engine->init_hw = init_ring_common;
        engine->reset.prepare = reset_prepare;
        engine->reset.reset = reset_ring;
        engine->reset.finish = reset_finish;

        engine->context_pin = intel_ring_context_pin;
        engine->request_alloc = ring_request_alloc;

        /*
         * Using a global execution timeline; the previous final breadcrumb is
         * equivalent to our next initial bread so we can elide
         * engine->emit_init_breadcrumb().
         */
        engine->emit_fini_breadcrumb = i9xx_emit_breadcrumb;
        if (IS_GEN(dev_priv, 5))
                engine->emit_fini_breadcrumb = gen5_emit_breadcrumb;

        engine->set_default_submission = i9xx_set_default_submission;

        if (INTEL_GEN(dev_priv) >= 6)
                engine->emit_bb_start = gen6_emit_bb_start;
        else if (INTEL_GEN(dev_priv) >= 4)
                engine->emit_bb_start = i965_emit_bb_start;
        else if (IS_I830(dev_priv) || IS_I845G(dev_priv))
                engine->emit_bb_start = i830_emit_bb_start;
        else
                engine->emit_bb_start = i915_emit_bb_start;
}

int intel_init_render_ring_buffer(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        intel_ring_default_vfuncs(dev_priv, engine);

        if (HAS_L3_DPF(dev_priv))
                engine->irq_keep_mask = GT_RENDER_L3_PARITY_ERROR_INTERRUPT;

        engine->irq_enable_mask = GT_RENDER_USER_INTERRUPT;

        if (INTEL_GEN(dev_priv) >= 7) {
                engine->init_context = intel_rcs_ctx_init;
                engine->emit_flush = gen7_render_ring_flush;
                engine->emit_fini_breadcrumb = gen7_rcs_emit_breadcrumb;
        } else if (IS_GEN(dev_priv, 6)) {
                engine->init_context = intel_rcs_ctx_init;
                engine->emit_flush = gen6_render_ring_flush;
                engine->emit_fini_breadcrumb = gen6_rcs_emit_breadcrumb;
        } else if (IS_GEN(dev_priv, 5)) {
                engine->emit_flush = gen4_render_ring_flush;
        } else {
                if (INTEL_GEN(dev_priv) < 4)
                        engine->emit_flush = gen2_render_ring_flush;
                else
                        engine->emit_flush = gen4_render_ring_flush;
                engine->irq_enable_mask = I915_USER_INTERRUPT;
        }

        if (IS_HASWELL(dev_priv))
                engine->emit_bb_start = hsw_emit_bb_start;

        engine->init_hw = init_render_ring;

        ret = intel_init_ring_buffer(engine);
        if (ret)
                return ret;

        return 0;
}

int intel_init_bsd_ring_buffer(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        intel_ring_default_vfuncs(dev_priv, engine);

        if (INTEL_GEN(dev_priv) >= 6) {
                /* gen6 bsd needs a special wa for tail updates */
                if (IS_GEN(dev_priv, 6))
                        engine->set_default_submission = gen6_bsd_set_default_submission;
                engine->emit_flush = gen6_bsd_ring_flush;
                engine->irq_enable_mask = GT_BSD_USER_INTERRUPT;

                if (IS_GEN(dev_priv, 6))
                        engine->emit_fini_breadcrumb = gen6_xcs_emit_breadcrumb;
                else
                        engine->emit_fini_breadcrumb = gen7_xcs_emit_breadcrumb;
        } else {
                engine->emit_flush = bsd_ring_flush;
                if (IS_GEN(dev_priv, 5))
                        engine->irq_enable_mask = ILK_BSD_USER_INTERRUPT;
                else
                        engine->irq_enable_mask = I915_BSD_USER_INTERRUPT;
        }

        return intel_init_ring_buffer(engine);
}

int intel_init_blt_ring_buffer(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        GEM_BUG_ON(INTEL_GEN(dev_priv) < 6);

        intel_ring_default_vfuncs(dev_priv, engine);

        engine->emit_flush = gen6_ring_flush;
        engine->irq_enable_mask = GT_BLT_USER_INTERRUPT;

        if (IS_GEN(dev_priv, 6))
                engine->emit_fini_breadcrumb = gen6_xcs_emit_breadcrumb;
        else
                engine->emit_fini_breadcrumb = gen7_xcs_emit_breadcrumb;

        return intel_init_ring_buffer(engine);
}

int intel_init_vebox_ring_buffer(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        GEM_BUG_ON(INTEL_GEN(dev_priv) < 7);

        intel_ring_default_vfuncs(dev_priv, engine);

        engine->emit_flush = gen6_ring_flush;
        engine->irq_enable_mask = PM_VEBOX_USER_INTERRUPT;
        engine->irq_enable = hsw_vebox_irq_enable;
        engine->irq_disable = hsw_vebox_irq_disable;

        engine->emit_fini_breadcrumb = gen7_xcs_emit_breadcrumb;

        return intel_init_ring_buffer(engine);
}