[Intel-gfx] [PATCH 4/5] drm/i915/ringbuffer: Remove irq-seqno w/a for gen6/7 rcs

[Chris Wilson]

Having transitioned to using PIPECONTROL to combine the flush with the
breadcrumb write using their post-sync functions, assume that this will
resolve the serialisation with the subsequent MI_USER_INTERRUPT. That is
when inspecting the breadcrumb after an interrupt we can rely on the write
being posted (i.e. the HWSP will be coherent).

Testing using gem_sync shows that the PIPECONTROL + CS stall does
serialise the command streamer sufficient that the breadcrumb lands
before the MI_USER_INTERRUPT. The same is not true for MI_FLUSH_DW.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_ringbuffer.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index eb3701fdeab6..5a1e4a65516e 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -2117,7 +2117,6 @@ static void intel_ring_init_irq(struct drm_i915_private *dev_priv,
 	if (INTEL_GEN(dev_priv) >= 6) {
 		engine->irq_enable = gen6_irq_enable;
 		engine->irq_disable = gen6_irq_disable;
-		engine->irq_seqno_barrier = gen6_seqno_barrier;
 	} else if (INTEL_GEN(dev_priv) >= 5) {
 		engine->irq_enable = gen5_irq_enable;
 		engine->irq_disable = gen5_irq_disable;
@@ -2236,6 +2235,8 @@ int intel_init_bsd_ring_buffer(struct intel_engine_cs *engine)
 
 		engine->emit_breadcrumb = gen6_xcs_emit_breadcrumb;
 		engine->emit_breadcrumb_sz = gen6_xcs_emit_breadcrumb_sz;
+
+		engine->irq_seqno_barrier = gen6_seqno_barrier;
 	} else {
 		engine->emit_flush = bsd_ring_flush;
 		if (IS_GEN(dev_priv, 5))
@@ -2260,6 +2261,7 @@ int intel_init_blt_ring_buffer(struct intel_engine_cs *engine)
 
 	engine->emit_breadcrumb = gen6_xcs_emit_breadcrumb;
 	engine->emit_breadcrumb_sz = gen6_xcs_emit_breadcrumb_sz;
+	engine->irq_seqno_barrier = gen6_seqno_barrier;
 
 	return intel_init_ring_buffer(engine);
 }
@@ -2279,6 +2281,7 @@ int intel_init_vebox_ring_buffer(struct intel_engine_cs *engine)
 
 	engine->emit_breadcrumb = gen6_xcs_emit_breadcrumb;
 	engine->emit_breadcrumb_sz = gen6_xcs_emit_breadcrumb_sz;
+	engine->irq_seqno_barrier = gen6_seqno_barrier;
 
 	return intel_init_ring_buffer(engine);
 }
-- 
2.20.0