From: Tim Gore <tim.gore@xxxxxxxxx>
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.
v2. Oops, add FLOW_CONTROL_ENABLE macro to i915_reg.h.
Signed-off-by: Tim Gore <tim.gore@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_reg.h | 1 +
drivers/gpu/drm/i915/intel_ringbuffer.c | 2 ++
2 files changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 7dfc400..58dcf01 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7103,6 +7103,7 @@ enum skl_disp_power_wells {
#define GEN9_CCS_TLB_PREFETCH_ENABLE (1<<3)
#define GEN8_ROW_CHICKEN _MMIO(0xe4f0)
+#define FLOW_CONTROL_ENABLE (1<<15)
#define PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE (1<<8)
#define STALL_DOP_GATING_DISABLE (1<<5)
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
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