[PATCH] drm/amdgpu/vcn: fix video profile race condition (v3)

[Alex Deucher]

If there are multiple instances of the VCN running,
we may end up switching the video profile while another
instance is active because we only take into account
the current instance's submissions.  Look at all
outstanding fences for the video profile.

v2: drop early exit in begin_use()
v3: handle possible race between begin_use() work handler

Fixes: 3b669df92c85 ("drm/amdgpu/vcn: adjust workload profile handling")
Reviewed-by: Sathishkumar S <sathishkumar.sundararaju at amd.com> (v1)
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.c | 40 ++++++++++++-------------
 drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h |  1 +
 2 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.c
index 9a76e11d1c184..593c1ddf8819b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.c
@@ -415,19 +415,25 @@ static void amdgpu_vcn_idle_work_handler(struct work_struct *work)
 	struct amdgpu_vcn_inst *vcn_inst =
 		container_of(work, struct amdgpu_vcn_inst, idle_work.work);
 	struct amdgpu_device *adev = vcn_inst->adev;
-	unsigned int fences = 0, fence[AMDGPU_MAX_VCN_INSTANCES] = {0};
-	unsigned int i = vcn_inst->inst, j;
+	unsigned int total_fences = 0, fence[AMDGPU_MAX_VCN_INSTANCES] = {0};
+	unsigned int i, j;
 	int r = 0;
 
-	if (adev->vcn.harvest_config & (1 << i))
+	if (adev->vcn.harvest_config & (1 << vcn_inst->inst))
 		return;
 
-	for (j = 0; j < adev->vcn.inst[i].num_enc_rings; ++j)
-		fence[i] += amdgpu_fence_count_emitted(&vcn_inst->ring_enc[j]);
+	for (i = 0; i < adev->vcn.num_vcn_inst; ++i) {
+		struct amdgpu_vcn_inst *v = &adev->vcn.inst[i];
+
+		for (j = 0; j < v->num_enc_rings; ++j)
+			fence[i] += amdgpu_fence_count_emitted(&v->ring_enc[j]);
+		fence[i] += amdgpu_fence_count_emitted(&v->ring_dec);
+		total_fences += fence[i];
+	}
 
 	/* Only set DPG pause for VCN3 or below, VCN4 and above will be handled by FW */
 	if (adev->pg_flags & AMD_PG_SUPPORT_VCN_DPG &&
-	    !adev->vcn.inst[i].using_unified_queue) {
+	    !vcn_inst->using_unified_queue) {
 		struct dpg_pause_state new_state;
 
 		if (fence[i] ||
@@ -436,18 +442,18 @@ static void amdgpu_vcn_idle_work_handler(struct work_struct *work)
 		else
 			new_state.fw_based = VCN_DPG_STATE__UNPAUSE;
 
-		adev->vcn.inst[i].pause_dpg_mode(vcn_inst, &new_state);
+		vcn_inst->pause_dpg_mode(vcn_inst, &new_state);
 	}
 
-	fence[i] += amdgpu_fence_count_emitted(&vcn_inst->ring_dec);
-	fences += fence[i];
-
-	if (!fences && !atomic_read(&vcn_inst->total_submission_cnt)) {
+	if (!fence[vcn_inst->inst] && !atomic_read(&vcn_inst->total_submission_cnt)) {
+		/* This is specific to this instance */
 		mutex_lock(&vcn_inst->vcn_pg_lock);
 		vcn_inst->set_pg_state(vcn_inst, AMD_PG_STATE_GATE);
 		mutex_unlock(&vcn_inst->vcn_pg_lock);
 		mutex_lock(&adev->vcn.workload_profile_mutex);
-		if (adev->vcn.workload_profile_active) {
+		/* This is global and depends on all VCN instances */
+		if (adev->vcn.workload_profile_active && !total_fences &&
+		    !atomic_read(&adev->vcn.total_submission_cnt)) {
 			r = amdgpu_dpm_switch_power_profile(adev, PP_SMC_POWER_PROFILE_VIDEO,
 							    false);
 			if (r)
@@ -467,16 +473,10 @@ void amdgpu_vcn_ring_begin_use(struct amdgpu_ring *ring)
 	int r = 0;
 
 	atomic_inc(&vcn_inst->total_submission_cnt);
+	atomic_inc(&adev->vcn.total_submission_cnt);
 
 	cancel_delayed_work_sync(&vcn_inst->idle_work);
 
-	/* We can safely return early here because we've cancelled the
-	 * the delayed work so there is no one else to set it to false
-	 * and we don't care if someone else sets it to true.
-	 */
-	if (adev->vcn.workload_profile_active)
-		goto pg_lock;
-
 	mutex_lock(&adev->vcn.workload_profile_mutex);
 	if (!adev->vcn.workload_profile_active) {
 		r = amdgpu_dpm_switch_power_profile(adev, PP_SMC_POWER_PROFILE_VIDEO,
@@ -487,7 +487,6 @@ void amdgpu_vcn_ring_begin_use(struct amdgpu_ring *ring)
 	}
 	mutex_unlock(&adev->vcn.workload_profile_mutex);
 
-pg_lock:
 	mutex_lock(&vcn_inst->vcn_pg_lock);
 	vcn_inst->set_pg_state(vcn_inst, AMD_PG_STATE_UNGATE);
 
@@ -528,6 +527,7 @@ void amdgpu_vcn_ring_end_use(struct amdgpu_ring *ring)
 		atomic_dec(&ring->adev->vcn.inst[ring->me].dpg_enc_submission_cnt);
 
 	atomic_dec(&ring->adev->vcn.inst[ring->me].total_submission_cnt);
+	atomic_dec(&ring->adev->vcn.total_submission_cnt);
 
 	schedule_delayed_work(&ring->adev->vcn.inst[ring->me].idle_work,
 			      VCN_IDLE_TIMEOUT);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
index b3fb1d0e43fc9..febc3ce8641ff 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
@@ -352,6 +352,7 @@ struct amdgpu_vcn {
 
 	uint16_t inst_mask;
 	uint8_t	num_inst_per_aid;
+	atomic_t		total_submission_cnt;
 
 	/* IP reg dump */
 	uint32_t		*ip_dump;
-- 
2.50.1