Messages in this thread | | | Date | Tue, 4 Apr 2023 17:22:39 +0100 | Subject | Re: [PATCH v2] drm/i915/gt: Hold a wakeref for the active VM | From | Tvrtko Ursulin <> |
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On 04/04/2023 17:00, Andi Shyti wrote: > Hi Tvrtko, > >>>> diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h >>>> index 0a8d553da3f439..48f888c3da083b 100644 >>>> --- a/drivers/gpu/drm/i915/gt/intel_context.h >>>> +++ b/drivers/gpu/drm/i915/gt/intel_context.h >>>> @@ -14,6 +14,7 @@ >>>> #include "i915_drv.h" >>>> #include "intel_context_types.h" >>>> #include "intel_engine_types.h" >>>> +#include "intel_gt_pm.h" >>>> #include "intel_ring_types.h" >>>> #include "intel_timeline_types.h" >>>> #include "i915_trace.h" >>>> @@ -207,8 +208,11 @@ void intel_context_exit_engine(struct intel_context *ce); >>>> static inline void intel_context_enter(struct intel_context *ce) >>>> { >>>> lockdep_assert_held(&ce->timeline->mutex); >>>> - if (!ce->active_count++) >>>> - ce->ops->enter(ce); >>>> + if (ce->active_count++) >>>> + return; >>>> + >>>> + ce->ops->enter(ce); >>>> + intel_gt_pm_get(ce->vm->gt); >>>> } >>>> static inline void intel_context_mark_active(struct intel_context *ce) >>>> @@ -222,8 +226,11 @@ static inline void intel_context_exit(struct intel_context *ce) >>>> { >>>> lockdep_assert_held(&ce->timeline->mutex); >>>> GEM_BUG_ON(!ce->active_count); >>>> - if (!--ce->active_count) >>>> - ce->ops->exit(ce); >>>> + if (--ce->active_count) >>>> + return; >>>> + >>>> + intel_gt_pm_put_async(ce->vm->gt); >>>> + ce->ops->exit(ce); >>> >>> shouldn't these two be swapped? > > maybe I wasn't clear here... shouldn't it be
I missed this one.
> ce->ops->exit(ce); > intel_gt_pm_put_async(ce->vm->gt); > > Don't we need to hold the pm until exiting?
I think it doesn't matter. The problematic edge case this is fixing is when ce->engine->gt is different from ce->vm->gt but at this point if it is safe to release one it must be safe to release the other too.
Regards,
Tvrtko
> >>>> } >>>> static inline struct intel_context *intel_context_get(struct intel_context *ce) >>>> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c >>>> index e971b153fda976..ee531a5c142c77 100644 >>>> --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c >>>> +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c >>>> @@ -114,6 +114,15 @@ __queue_and_release_pm(struct i915_request *rq, >>>> ENGINE_TRACE(engine, "parking\n"); >>>> + /* >>>> + * Open coded one half of intel_context_enter, which we have to omit >>>> + * here (see the large comment below) and because the other part must >>>> + * not be called due constructing directly with __i915_request_create >>>> + * which increments active count via intel_context_mark_active. >>>> + */ >>>> + GEM_BUG_ON(rq->context->active_count != 1); >>>> + __intel_gt_pm_get(engine->gt); >>> >>> where is it's brother "put"? >> >> It's in request retire via intel_context_exit. Ie. request construction is >> special here, while retirement is standard. > > Thank you! > Andi
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