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* [PATCH] drm/i915/gt: Try an extra flush on the Haswell blitter
@ 2019-11-11 12:09 ` Chris Wilson
  0 siblings, 0 replies; 10+ messages in thread
From: Chris Wilson @ 2019-11-11 12:09 UTC (permalink / raw)
  To: intel-gfx

On gen7, including Haswell, the MI_FLUSH_DW command is not synchronous
with the command streamer nor is there an option to make it so. To hide
this we add a large delay on the CS so that the breadcrumb should always
be visible before the interrupt. However, that does not seem to be
enough to ensure the memory is actually coherent with the read of the
breadcrumb. The breadcrumb update is a post-sync op... Throw in a
preliminary MI_FLUSH_DW before the breadcrumb update in the hope that
helps.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112147
Testcase: igt/i915_selftest/live_blt
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/intel_ring_submission.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index a47d5a7c32c9..fc29df712810 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -454,6 +454,10 @@ static u32 *gen7_xcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
 	GEM_BUG_ON(i915_request_active_timeline(rq)->hwsp_ggtt != rq->engine->status_page.vma);
 	GEM_BUG_ON(offset_in_page(i915_request_active_timeline(rq)->hwsp_offset) != I915_GEM_HWS_SEQNO_ADDR);
 
+	*cs++ = MI_FLUSH_DW;
+	*cs++ = 0;
+	*cs++ = 0;
+
 	*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;
@@ -469,7 +473,6 @@ static u32 *gen7_xcs_emit_breadcrumb(struct i915_request *rq, u32 *cs)
 	*cs++ = 0;
 
 	*cs++ = MI_USER_INTERRUPT;
-	*cs++ = MI_NOOP;
 
 	rq->tail = intel_ring_offset(rq, cs);
 	assert_ring_tail_valid(rq->ring, rq->tail);
-- 
2.24.0

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^ permalink raw reply related	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2019-11-12 14:06 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2019-11-11 12:09 [PATCH] drm/i915/gt: Try an extra flush on the Haswell blitter Chris Wilson
2019-11-11 12:09 ` [Intel-gfx] " Chris Wilson
2019-11-11 18:45 ` ✓ Fi.CI.BAT: success for " Patchwork
2019-11-11 18:45   ` [Intel-gfx] " Patchwork
2019-11-12  6:33 ` ✓ Fi.CI.IGT: " Patchwork
2019-11-12  6:33   ` [Intel-gfx] " Patchwork
2019-11-12 13:58 ` [PATCH] " Mika Kuoppala
2019-11-12 13:58   ` [Intel-gfx] " Mika Kuoppala
2019-11-12 14:06   ` Chris Wilson
2019-11-12 14:06     ` [Intel-gfx] " Chris Wilson

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