From b06b8103ae3e05ef9a638a5973c75bd6962733db Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Sun, 17 Jan 2021 11:04:18 +0000 Subject: [PATCH] drm/i915/gt: Add arbitration check before semaphore wait Similar to commit 49b20dbf7497 ("drm/i915/gt: Perform an arbitration check before busywaiting"), also add a check prior to the busywait on gen8+, as we have now seen (because we added a selftest to add fault injection into the engine resets) the same engine reset failure leading to an indefinite wait on the ring-stop semaphore. So not a Tigerlake specific bug after all, though it still seems odd behaviour for the busywait as we do get the arbitration point elsewhere on a miss. Testcase: igt_reset_fail_engine Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20210117110418.3361-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/gt/gen8_engine_cs.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c index 5b932d2..07ba524 100644 --- a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c @@ -488,6 +488,7 @@ static u32 *gen8_emit_wa_tail(struct i915_request *rq, u32 *cs) static u32 *emit_preempt_busywait(struct i915_request *rq, u32 *cs) { + *cs++ = MI_ARB_CHECK; /* trigger IDLE->ACTIVE first */ *cs++ = MI_SEMAPHORE_WAIT | MI_SEMAPHORE_GLOBAL_GTT | MI_SEMAPHORE_POLL | @@ -495,6 +496,7 @@ static u32 *emit_preempt_busywait(struct i915_request *rq, u32 *cs) *cs++ = 0; *cs++ = preempt_address(rq->engine); *cs++ = 0; + *cs++ = MI_NOOP; return cs; } -- 2.7.4