[Intel-gfx] [PATCH] drm/i915/gen9: add WaClearFlowControlGpgpuContextSave

[tim.gore at intel.com]

From: Tim Gore <tim.gore at intel.com>

This allows writes to EU flow control registers. Together
with SIP code from the user-mode driver this resolves a
hang seen in some pre-emption scenarios. Note that this
patch is just the kernel mode part of this workaround.

Signed-off-by: Tim Gore <tim.gore at intel.com>
---
 drivers/gpu/drm/i915/intel_ringbuffer.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 45ce45a..83ab25a 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -920,8 +920,10 @@ static int gen9_init_workarounds(struct intel_engine_cs *ring)
 	I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
 		   ECOCHK_DIS_TLB);
 
+	/* WaClearFlowControlGpgpuContextSave:skl,bxt */
 	/* WaDisablePartialInstShootdown:skl,bxt */
 	WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
+			  FLOW_CONTROL_ENABLE |
 			  PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE);
 
 	/* Syncing dependencies between camera and graphics:skl,bxt */
-- 
1.9.1