On 6/24/2021 00:04, Matthew Brost wrote:
Semaphores are an optimization and not required for basic GuC submission
to work properly. Disable until we have time to do the implementation to
enable semaphores and tune them for performance. Also long direction is
just to delete semaphores from the i915 so another reason to not enable
these for GuC submission.
v2: Reword commit message
Cc: John Harrison <john.c.harrison@xxxxxxxxx>
Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
I think the commit description does not really match the patch content.
The description is valid but the 'disable' is done by simply not setting
the enable flag (done in the execlist back end and presumably not done
in the GuC back end). However, what the patch is actually doing seems to
be fixing bugs with the 'are semaphores enabled' mechanism. I.e.
correcting pieces of code that used semaphores without checking if they
are enabled. And presumably this would be broken if someone tried to
disable semaphores in execlist mode for any reason?
So I think keeping the existing comment text is fine but something
should be added to explain the actual changes.
John.
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 7720b8c22c81..5c07e6abf16a 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -230,7 +230,8 @@ static void intel_context_set_gem(struct intel_context *ce,
ce->timeline = intel_timeline_get(ctx->timeline);
if (ctx->sched.priority >= I915_PRIORITY_NORMAL &&
- intel_engine_has_timeslices(ce->engine))
+ intel_engine_has_timeslices(ce->engine) &&
+ intel_engine_has_semaphores(ce->engine))
__set_bit(CONTEXT_USE_SEMAPHORES, &ce->flags);
intel_context_set_watchdog_us(ce, ctx->watchdog.timeout_us);
@@ -1938,7 +1939,8 @@ static int __apply_priority(struct intel_context *ce, void *arg)
if (!intel_engine_has_timeslices(ce->engine))
return 0;
- if (ctx->sched.priority >= I915_PRIORITY_NORMAL)
+ if (ctx->sched.priority >= I915_PRIORITY_NORMAL &&
+ intel_engine_has_semaphores(ce->engine))
intel_context_set_use_semaphores(ce);
else
intel_context_clear_use_semaphores(ce);
