From: Ville Syrjälä Date: Tue, 14 Oct 2025 19:18:06 +0000 (+0300) Subject: drm/i915/wm: Add WM0 prefill helpers X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=9704c1cbedfd05a6a29017d580a2819964420511;p=thirdparty%2Fkernel%2Flinux.git drm/i915/wm: Add WM0 prefill helpers Add skl_wm0_prefill_lines() (based on the actual state) and skl_wm0_prefill_lines_worst() (worst case estimate) which tell us how many extra lines are needed in prefill for WM0. The returned numbers are in .16 binary fixed point. TODO: skl_wm0_prefill_lines_worst() is a bit rough still v2: Drop all pre-icl FIXMEs since this only gets used for VRR guardband Reviewed-by: Uma Shankar #v1 Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20251014191808.12326-8-ville.syrjala@linux.intel.com --- diff --git a/drivers/gpu/drm/i915/display/skl_scaler.c b/drivers/gpu/drm/i915/display/skl_scaler.c index 630fcf1cb9acc..d29efcbf2319f 100644 --- a/drivers/gpu/drm/i915/display/skl_scaler.c +++ b/drivers/gpu/drm/i915/display/skl_scaler.c @@ -1026,7 +1026,37 @@ static unsigned int _skl_scaler_max_scale(const struct intel_crtc_state *crtc_st crtc_state->hw.pipe_mode.crtc_clock)); } -static unsigned int skl_scaler_max_scale(const struct intel_crtc_state *crtc_state) +unsigned int skl_scaler_max_total_scale(const struct intel_crtc_state *crtc_state) +{ + struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc); + unsigned int max_scale; + + if (crtc->num_scalers < 1) + return 0x10000; + + /* FIXME find out the max downscale factors properly */ + max_scale = 9 << 16; + if (crtc->num_scalers > 1) + max_scale *= 9; + + return _skl_scaler_max_scale(crtc_state, max_scale); +} + +unsigned int skl_scaler_max_hscale(const struct intel_crtc_state *crtc_state) +{ + struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc); + unsigned int max_scale; + + if (crtc->num_scalers < 1) + return 0x10000; + + /* FIXME find out the max downscale factors properly */ + max_scale = 3 << 16; + + return _skl_scaler_max_scale(crtc_state, max_scale); +} + +unsigned int skl_scaler_max_scale(const struct intel_crtc_state *crtc_state) { struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc); unsigned int max_scale; diff --git a/drivers/gpu/drm/i915/display/skl_scaler.h b/drivers/gpu/drm/i915/display/skl_scaler.h index 6fab40d2b4ee5..5deabca909e65 100644 --- a/drivers/gpu/drm/i915/display/skl_scaler.h +++ b/drivers/gpu/drm/i915/display/skl_scaler.h @@ -46,6 +46,10 @@ void adl_scaler_ecc_mask(const struct intel_crtc_state *crtc_state); void adl_scaler_ecc_unmask(const struct intel_crtc_state *crtc_state); +unsigned int skl_scaler_max_total_scale(const struct intel_crtc_state *crtc_state); +unsigned int skl_scaler_max_scale(const struct intel_crtc_state *crtc_state); +unsigned int skl_scaler_max_hscale(const struct intel_crtc_state *crtc_state); + unsigned int skl_scaler_1st_prefill_adjustment_worst(const struct intel_crtc_state *crtc_state); unsigned int skl_scaler_2nd_prefill_adjustment_worst(const struct intel_crtc_state *crtc_state); unsigned int skl_scaler_1st_prefill_lines_worst(const struct intel_crtc_state *crtc_state); diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c index 06e5e6c77d2ed..700707a91c704 100644 --- a/drivers/gpu/drm/i915/display/skl_watermark.c +++ b/drivers/gpu/drm/i915/display/skl_watermark.c @@ -30,6 +30,7 @@ #include "intel_plane.h" #include "intel_vblank.h" #include "intel_wm.h" +#include "skl_scaler.h" #include "skl_universal_plane_regs.h" #include "skl_watermark.h" #include "skl_watermark_regs.h" @@ -2245,6 +2246,57 @@ skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state, intel_crtc_vblank_length(crtc_state); } +unsigned int skl_wm0_prefill_lines_worst(const struct intel_crtc_state *crtc_state) +{ + struct intel_display *display = to_intel_display(crtc_state); + struct intel_plane *plane = to_intel_plane(crtc_state->uapi.crtc->primary); + const struct drm_display_mode *pipe_mode = &crtc_state->hw.pipe_mode; + int ret, pixel_rate, width, level = 0; + const struct drm_format_info *info; + struct skl_wm_level wm = {}; + struct skl_wm_params wp; + unsigned int latency; + u64 modifier; + u32 format; + + /* only expected to be used for VRR guardband calculation */ + drm_WARN_ON(display->drm, !HAS_VRR(display)); + + /* FIXME rather ugly to pick this by hand but maybe no better way? */ + format = DRM_FORMAT_XBGR16161616F; + if (HAS_4TILE(display)) + modifier = I915_FORMAT_MOD_4_TILED; + else + modifier = I915_FORMAT_MOD_Y_TILED; + + info = drm_get_format_info(display->drm, format, modifier); + + pixel_rate = DIV_ROUND_UP_ULL(mul_u32_u32(skl_scaler_max_total_scale(crtc_state), + pipe_mode->crtc_clock), + 0x10000); + + /* FIXME limit to max plane width? */ + width = DIV_ROUND_UP_ULL(mul_u32_u32(skl_scaler_max_hscale(crtc_state), + pipe_mode->crtc_hdisplay), + 0x10000); + + /* FIXME is 90/270 rotation worse than 0/180? */ + ret = skl_compute_wm_params(crtc_state, width, info, + modifier, DRM_MODE_ROTATE_0, + pixel_rate, &wp, 0, 1); + drm_WARN_ON(display->drm, ret); + + latency = skl_wm_latency(display, level, &wp); + + skl_compute_plane_wm(crtc_state, plane, level, latency, &wp, &wm, &wm); + + /* FIXME is this sane? */ + if (wm.min_ddb_alloc == U16_MAX) + wm.lines = skl_wm_max_lines(display); + + return wm.lines << 16; +} + static int skl_max_wm0_lines(const struct intel_crtc_state *crtc_state) { struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc); @@ -2261,6 +2313,11 @@ static int skl_max_wm0_lines(const struct intel_crtc_state *crtc_state) return wm0_lines; } +unsigned int skl_wm0_prefill_lines(const struct intel_crtc_state *crtc_state) +{ + return skl_max_wm0_lines(crtc_state) << 16; +} + /* * TODO: In case we use PKG_C_LATENCY to allow C-states when the delayed vblank * size is too small for the package C exit latency we need to notify PSR about diff --git a/drivers/gpu/drm/i915/display/skl_watermark.h b/drivers/gpu/drm/i915/display/skl_watermark.h index 62790816f030d..6bc2ec9164bfc 100644 --- a/drivers/gpu/drm/i915/display/skl_watermark.h +++ b/drivers/gpu/drm/i915/display/skl_watermark.h @@ -79,5 +79,8 @@ void intel_program_dpkgc_latency(struct intel_atomic_state *state); bool intel_dbuf_pmdemand_needs_update(struct intel_atomic_state *state); +unsigned int skl_wm0_prefill_lines_worst(const struct intel_crtc_state *crtc_state); +unsigned int skl_wm0_prefill_lines(const struct intel_crtc_state *crtc_state); + #endif /* __SKL_WATERMARK_H__ */