[Intel-gfx] [PATCH] drm/i915/guc: Disable preemption if it fails

[Chris Wilson]

If we fail to tell the GuC to perform preemption, we get stuck
attempting to continually retry inject_preempt_context() until we
eventually timeout and reset the GPU (approximately emitting the same
warning 1000 times). Bail after the first failure, emit the WARN and
stop trying to do any further preemption on this engine.

References: https://intel-gfx-ci.01.org/tree/drm-tip/Trybot_2235/shard-apl4/igt@gem_exec_schedule@preempt-bsd.html
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Michel Thierry <michel.thierry at intel.com>
Cc: Michałt Winiarski <michal.winiarski at intel.com>
---
 drivers/gpu/drm/i915/intel_guc_submission.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c b/drivers/gpu/drm/i915/intel_guc_submission.c
index 133367a17863..24bdac205c45 100644
--- a/drivers/gpu/drm/i915/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/intel_guc_submission.c
@@ -588,6 +588,7 @@ static void inject_preempt_context(struct work_struct *work)
 	data[6] = intel_guc_ggtt_offset(guc, guc->shared_data);
 
 	if (WARN_ON(intel_guc_send(guc, data, ARRAY_SIZE(data)))) {
+		engine->flags &= ~I915_ENGINE_HAS_PREEMPTION; /* XXX racy! */
 		execlists_clear_active(&engine->execlists,
 				       EXECLISTS_ACTIVE_PREEMPT);
 		tasklet_schedule(&engine->execlists.tasklet);
-- 
2.17.1