From: Greg Kroah-Hartman Date: Tue, 7 Aug 2012 07:54:14 +0000 (+0200) Subject: Revert "drm/i915: correctly order the ring init sequence" X-Git-Tag: v3.5.7~13 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0ba9e491a36eb07bf2fb7f43b6c374bea07c6834;p=thirdparty%2Fkernel%2Fstable.git Revert "drm/i915: correctly order the ring init sequence" This reverts 622ecb9ace2ec006b58f6779732961945ea303ca which is commit 0d8957c8a90bbb5d34fab9a304459448a5131e06 upstream. We may only start to set up the new register values after having confirmed that the ring is truely off. Otherwise the hw might lose the newly written register values. This is caught later on in the init sequence, when we check whether the register writes have stuck. Reported-by: Andreas Sturmlechner Cc: Jani Nikula Cc: Yang Guang Cc: Daniel Vetter Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index b5e7bd9e1f8fb..e5b84ff89ca58 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -280,6 +280,8 @@ static int init_ring_common(struct intel_ring_buffer *ring) I915_WRITE_HEAD(ring, 0); ring->write_tail(ring, 0); + /* Initialize the ring. */ + I915_WRITE_START(ring, obj->gtt_offset); head = I915_READ_HEAD(ring) & HEAD_ADDR; /* G45 ring initialization fails to reset head to zero */ @@ -305,11 +307,6 @@ static int init_ring_common(struct intel_ring_buffer *ring) } } - /* 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(ring, obj->gtt_offset); I915_WRITE_CTL(ring, ((ring->size - PAGE_SIZE) & RING_NR_PAGES) | RING_VALID);