Don't check CT descriptor status, unless CONFIG_DRM_I915_DEBUG_GUC is set, before CT write / read as this could result in a read across the PCIe bus thus adding latency to every CT write / read. On well behavied systems this vaue should always read as zero. For some reason it doesn't the CT channel is broken and will eventually recover from a GT reset, albeit the GT reset will not be triggered immediately by seeing that descriptor status is non-zero.
v2: (CI) - Fix build error (hide corrupted label in write function behind CONFIG_DRM_I915_DEBUG_GUC)
Signed-off-by: Matthew Brost matthew.brost@intel.com --- drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c index de89d40abd38d..948cf31429412 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c @@ -379,8 +379,10 @@ static int ct_write(struct intel_guc_ct *ct, u32 *cmds = ctb->cmds; unsigned int i;
+#ifdef CONFIG_DRM_I915_DEBUG_GUC if (unlikely(desc->status)) goto corrupted; +#endif
GEM_BUG_ON(tail > size);
@@ -445,11 +447,13 @@ static int ct_write(struct intel_guc_ct *ct,
return 0;
+#ifdef CONFIG_DRM_I915_DEBUG_GUC corrupted: CT_ERROR(ct, "Corrupted descriptor head=%u tail=%u status=%#x\n", desc->head, desc->tail, desc->status); ctb->broken = true; return -EPIPE; +#endif }
/** @@ -815,8 +819,10 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) if (unlikely(ctb->broken)) return -EPIPE;
+#ifdef CONFIG_DRM_I915_DEBUG_GUC if (unlikely(desc->status)) goto corrupted; +#endif
GEM_BUG_ON(head > size);