drm/amdgpu/vcn: fix race condition issue for vcn start

Fix race condition issue when multiple vcn starts are called.

v2: Removed checking the return value of cancel_delayed_work_sync()
to prevent possible races here.

v3: Add total_submission_cnt to avoid gate power unexpectedly.

v4: Remove extra counter check, and reduce counter before idle
work schedule

Signed-off-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.c
index f55e241..3ca3668 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.c
@@ -63,6 +63,8 @@ int amdgpu_vcn_sw_init(struct amdgpu_device *adev)
        int i, r;
 
        INIT_DELAYED_WORK(&adev->vcn.idle_work, amdgpu_vcn_idle_work_handler);
+       mutex_init(&adev->vcn.vcn_pg_lock);
+       atomic_set(&adev->vcn.total_submission_cnt, 0);
 
        switch (adev->asic_type) {
        case CHIP_RAVEN:
@@ -210,6 +212,7 @@ int amdgpu_vcn_sw_fini(struct amdgpu_device *adev)
        }
 
        release_firmware(adev->vcn.fw);
+       mutex_destroy(&adev->vcn.vcn_pg_lock);
 
        return 0;
 }
@@ -307,7 +310,7 @@ static void amdgpu_vcn_idle_work_handler(struct work_struct *work)
                fences += fence[j];
        }
 
-       if (fences == 0) {
+       if (!fences && !atomic_read(&adev->vcn.total_submission_cnt)) {
                amdgpu_gfx_off_ctrl(adev, true);
                amdgpu_device_ip_set_powergating_state(adev, AMD_IP_BLOCK_TYPE_VCN,
                       AMD_PG_STATE_GATE);
@@ -319,13 +322,14 @@ static void amdgpu_vcn_idle_work_handler(struct work_struct *work)
 void amdgpu_vcn_ring_begin_use(struct amdgpu_ring *ring)
 {
        struct amdgpu_device *adev = ring->adev;
-       bool set_clocks = !cancel_delayed_work_sync(&adev->vcn.idle_work);
 
-       if (set_clocks) {
-               amdgpu_gfx_off_ctrl(adev, false);
-               amdgpu_device_ip_set_powergating_state(adev, AMD_IP_BLOCK_TYPE_VCN,
-                      AMD_PG_STATE_UNGATE);
-       }
+       atomic_inc(&adev->vcn.total_submission_cnt);
+       cancel_delayed_work_sync(&adev->vcn.idle_work);
+
+       mutex_lock(&adev->vcn.vcn_pg_lock);
+       amdgpu_gfx_off_ctrl(adev, false);
+       amdgpu_device_ip_set_powergating_state(adev, AMD_IP_BLOCK_TYPE_VCN,
+              AMD_PG_STATE_UNGATE);
 
        if (adev->pg_flags & AMD_PG_SUPPORT_VCN_DPG)    {
                struct dpg_pause_state new_state;
@@ -345,10 +349,13 @@ void amdgpu_vcn_ring_begin_use(struct amdgpu_ring *ring)
 
                adev->vcn.pause_dpg_mode(adev, ring->me, &new_state);
        }
+       mutex_unlock(&adev->vcn.vcn_pg_lock);
 }
 
 void amdgpu_vcn_ring_end_use(struct amdgpu_ring *ring)
 {
+       atomic_dec(&ring->adev->vcn.total_submission_cnt);
+
        schedule_delayed_work(&ring->adev->vcn.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 6fe0573..111c4cc 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
@@ -200,6 +200,8 @@ struct amdgpu_vcn {
        struct drm_gpu_scheduler *vcn_dec_sched[AMDGPU_MAX_VCN_INSTANCES];
        uint32_t                 num_vcn_enc_sched;
        uint32_t                 num_vcn_dec_sched;
+       struct mutex             vcn_pg_lock;
+       atomic_t                 total_submission_cnt;
 
        unsigned        harvest_config;
        int (*pause_dpg_mode)(struct amdgpu_device *adev,