drm/amdgpu/vcn: Hold pg_lock before vcn power off

Acquire vcn_pg_lock before changes to vcn power state
and release it after power off in idle work handler.

Signed-off-by: Sathishkumar S <sathishkumar.sundararaju@amd.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: pldrc

drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.c

@@ -443,7 +443,9 @@ static void amdgpu_vcn_idle_work_handler(struct work_struct *work)
 	fences += fence[i];
 
 	if (!fences && !atomic_read(&vcn_inst->total_submission_cnt)) {
+		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) {
 			r = amdgpu_dpm_switch_power_profile(adev, PP_SMC_POWER_PROFILE_VIDEO,