Merge "drm/msm: Fix race condition in the submit path" (17273e15) · Commits · e / devices / android_kernel_sony_msm8998

drivers/gpu/drm/msm/adreno/a5xx_gpu.h

+7 −1

Original line number	Diff line number	Diff line
		@@ -70,6 +70,8 @@ struct a5xx_gpu {
		* PREEMPT_NONE - no preemption in progress. Next state START.
		* PREEMPT_START - The trigger is evaulating if preemption is possible. Next
		* states: TRIGGERED, NONE
		* PREEMPT_ABORT - An intermediate state before moving back to NONE. Next
		* state: NONE.
		* PREEMPT_TRIGGERED: A preemption has been executed on the hardware. Next
		* states: FAULTED, PENDING
		* PREEMPT_FAULTED: A preemption timed out (never completed). This will trigger
		@@ -81,6 +83,7 @@ struct a5xx_gpu {
		enum preempt_state {
		PREEMPT_NONE = 0,
		PREEMPT_START,
		PREEMPT_ABORT,
		PREEMPT_TRIGGERED,
		PREEMPT_FAULTED,
		PREEMPT_PENDING,
		@@ -184,7 +187,10 @@ int a5xx_snapshot(struct msm_gpu gpu, struct msm_snapshot snapshot);
		/* Return true if we are in a preempt state */
		static inline bool a5xx_in_preempt(struct a5xx_gpu *a5xx_gpu)
		{
		return !(atomic_read(&a5xx_gpu->preempt_state) == PREEMPT_NONE);
		int preempt_state = atomic_read(&a5xx_gpu->preempt_state);

		return !(preempt_state == PREEMPT_NONE \|\|
		preempt_state == PREEMPT_ABORT);
		}

		int a5xx_counters_init(struct adreno_gpu *adreno_gpu);

+14 −3

Original line number	Diff line number	Diff line
		@@ -128,9 +128,20 @@ void a5xx_preempt_trigger(struct msm_gpu *gpu)
		* one do nothing except to update the wptr to the latest and greatest
		*/
		if (!ring \|\| (a5xx_gpu->cur_ring == ring)) {
		update_wptr(gpu, ring);
		/*
		* Its possible that while a preemption request is in progress
		* from an irq context, a user context trying to submit might
		* fail to update the write pointer, because it determines
		* that the preempt state is not PREEMPT_NONE.
		*
		* Close the race by introducing an intermediate
		* state PREEMPT_ABORT to let the submit path
		* know that the ringbuffer is not going to change
		* and can safely update the write pointer.
		*/

		/* Set the state back to NONE */
		set_preempt_state(a5xx_gpu, PREEMPT_ABORT);
		update_wptr(gpu, a5xx_gpu->cur_ring);
		set_preempt_state(a5xx_gpu, PREEMPT_NONE);
		return;
		}