On 02/09/15 23:52, yu.dai@xxxxxxxxx wrote:
From: Alex Dai <yu.dai@xxxxxxxxx>
Bit 16 of GuC status indicates resuming from RC6. The LAPIC_DONE
status is a reliable readiness flag only when resuming from RC6.
This fix a racing issue that allocation of doorbell fails whilst
GuC init is not finished.
Signed-off-by: Alex Dai <yu.dai@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_guc_reg.h | 1 +
drivers/gpu/drm/i915/intel_guc_loader.c | 5 +++--
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_guc_reg.h b/drivers/gpu/drm/i915/i915_guc_reg.h
index 8c8e574..dd0e1e8 100644
--- a/drivers/gpu/drm/i915/i915_guc_reg.h
+++ b/drivers/gpu/drm/i915/i915_guc_reg.h
@@ -37,6 +37,7 @@
#define GS_UKERNEL_READY (0xF0 << GS_UKERNEL_SHIFT)
#define GS_MIA_SHIFT 16
#define GS_MIA_MASK (0x07 << GS_MIA_SHIFT)
+#define GS_MIA_CORE_STATE (1 << GS_MIA_SHIFT)
#define SOFT_SCRATCH(n) (0xc180 + ((n) * 4))
diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
index 5eafd31..5823615 100644
--- a/drivers/gpu/drm/i915/intel_guc_loader.c
+++ b/drivers/gpu/drm/i915/intel_guc_loader.c
@@ -209,9 +209,10 @@ static inline bool guc_ucode_response(struct drm_i915_private *dev_priv,
u32 *status)
{
u32 val = I915_READ(GUC_STATUS);
+ u32 uk_val = val & GS_UKERNEL_MASK;
*status = val;
- return ((val & GS_UKERNEL_MASK) == GS_UKERNEL_READY ||
- (val & GS_UKERNEL_MASK) == GS_UKERNEL_LAPIC_DONE);
+ return (uk_val == GS_UKERNEL_READY ||
+ ((val & GS_MIA_CORE_STATE) && uk_val == GS_UKERNEL_LAPIC_DONE));
}
/*
This does indeed fix the problem of not being able to *re*initialise the
GuC correctly after a hang/reset/reload cycle :) However I think the
last line looks quite confusing, especially because of the mix of
bitwise and logical operators (we have &, &&, and || all in one expression).
So I think it might be clearer if spelled out in two stages:
{
u32 val = I915_READ(GUC_STATUS);
+ u32 uk_val = val & GS_UKERNEL_MASK;
*status = val;
- return ((val & GS_UKERNEL_MASK) == GS_UKERNEL_READY ||
- (val & GS_UKERNEL_MASK) == GS_UKERNEL_LAPIC_DONE);
+
+ /* Iff resuming from RC6, look for LAPIC_DONE */
+ if (val & GS_MIA_CORE_STATE)
+ if (uk_val == GS_UKERNEL_LAPIC_DONE)
+ return true;
+
+ /* Otherwise just check whether the uKernel is READY */
+ return uk_val == GS_UKERNEL_READY;
}
Other than that I'm quite happy with it, so either version gets a
Reviewed-by: Dave Gordon <david.s.gordon@xxxxxxxxx>
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