[Intel-gfx] [PATCH v2] drm/i915/gt: Flush gen7 even harder

[Chris Wilson]

live_blt is still failing on hsw, showing the hallmark of incoherency.
Since we are fairly certain that the interrupt is after the seqno is
visible, the other possibility is that the seqno is before the writes to
memory are flushed. Throw in an TLB invalidate before the breadcrumb as
we are reasonably confident that forces a CS stall.

References: f9228f765873 ("drm/i915/gt: Try an extra flush on the Haswell blitter")
References: https://bugs.freedesktop.org/show_bug.cgi?id=112147
Testcase: igt/i915_selftest/live_blt
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
---
Try Mika's suggestion of an invalidate first.
---
 drivers/gpu/drm/i915/gt/intel_ring_submission.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index fc29df712810..e8bee44add34 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -454,8 +454,9 @@ 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++ = (MI_FLUSH_DW | MI_INVALIDATE_TLB |
+		 MI_FLUSH_DW_STORE_INDEX | MI_FLUSH_DW_OP_STOREDW);
+	*cs++ = I915_GEM_HWS_SCRATCH_ADDR | MI_FLUSH_DW_USE_GTT;
 	*cs++ = 0;
 
 	*cs++ = MI_FLUSH_DW | MI_FLUSH_DW_OP_STOREDW | MI_FLUSH_DW_STORE_INDEX;
-- 
2.24.0