drm/amd/powerplay: a quick fix for the deadlock issue below

NFO: task ocltst:2028 blocked for more than 120 seconds.
     Tainted: G           OE     5.0.0-37-generic #40~18.04.1-Ubuntu
echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
cltst          D    0  2028   2026 0x00000000
all Trace:
__schedule+0x2c0/0x870
schedule+0x2c/0x70
schedule_preempt_disabled+0xe/0x10
__mutex_lock.isra.9+0x26d/0x4e0
__mutex_lock_slowpath+0x13/0x20
? __mutex_lock_slowpath+0x13/0x20
mutex_lock+0x2f/0x40
amdgpu_dpm_set_powergating_by_smu+0x64/0xe0 [amdgpu]
gfx_v8_0_enable_gfx_static_mg_power_gating+0x3c/0x70 [amdgpu]
gfx_v8_0_set_powergating_state+0x66/0x260 [amdgpu]
amdgpu_device_ip_set_powergating_state+0x62/0xb0 [amdgpu]
pp_dpm_force_performance_level+0xe7/0x100 [amdgpu]
amdgpu_set_dpm_forced_performance_level+0x129/0x330 [amdgpu]

Fixes: a64c9e15e624 ("drm/amd/powerplay: cleanup the interfaces for powergate setting through SMU")
Signed-off-by: Evan Quan <evan.quan@amd.com>
Reported-by: Rui Teng <Rui.Teng@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dpm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dpm.c
index 6c7dca1..a2e8c3d 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dpm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dpm.c
@@ -946,23 +946,54 @@ int amdgpu_dpm_set_powergating_by_smu(struct amdgpu_device *adev, uint32_t block
        bool swsmu = is_support_sw_smu(adev);
 
        switch (block_type) {
-       case AMD_IP_BLOCK_TYPE_GFX:
        case AMD_IP_BLOCK_TYPE_UVD:
-       case AMD_IP_BLOCK_TYPE_VCN:
        case AMD_IP_BLOCK_TYPE_VCE:
-       case AMD_IP_BLOCK_TYPE_SDMA:
                if (swsmu) {
                        ret = smu_dpm_set_power_gate(&adev->smu, block_type, gate);
-               } else {
-                       if (adev->powerplay.pp_funcs &&
-                           adev->powerplay.pp_funcs->set_powergating_by_smu) {
-                               mutex_lock(&adev->pm.mutex);
-                               ret = ((adev)->powerplay.pp_funcs->set_powergating_by_smu(
-                                       (adev)->powerplay.pp_handle, block_type, gate));
-                               mutex_unlock(&adev->pm.mutex);
-                       }
+               } else if (adev->powerplay.pp_funcs &&
+                          adev->powerplay.pp_funcs->set_powergating_by_smu) {
+                       /*
+                        * TODO: need a better lock mechanism
+                        *
+                        * Here adev->pm.mutex lock protection is enforced on
+                        * UVD and VCE cases only. Since for other cases, there
+                        * may be already lock protection in amdgpu_pm.c.
+                        * This is a quick fix for the deadlock issue below.
+                        *     NFO: task ocltst:2028 blocked for more than 120 seconds.
+                        *     Tainted: G           OE     5.0.0-37-generic #40~18.04.1-Ubuntu
+                        *     echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
+                        *     cltst          D    0  2028   2026 0x00000000
+                        *     all Trace:
+                        *     __schedule+0x2c0/0x870
+                        *     schedule+0x2c/0x70
+                        *     schedule_preempt_disabled+0xe/0x10
+                        *     __mutex_lock.isra.9+0x26d/0x4e0
+                        *     __mutex_lock_slowpath+0x13/0x20
+                        *     ? __mutex_lock_slowpath+0x13/0x20
+                        *     mutex_lock+0x2f/0x40
+                        *     amdgpu_dpm_set_powergating_by_smu+0x64/0xe0 [amdgpu]
+                        *     gfx_v8_0_enable_gfx_static_mg_power_gating+0x3c/0x70 [amdgpu]
+                        *     gfx_v8_0_set_powergating_state+0x66/0x260 [amdgpu]
+                        *     amdgpu_device_ip_set_powergating_state+0x62/0xb0 [amdgpu]
+                        *     pp_dpm_force_performance_level+0xe7/0x100 [amdgpu]
+                        *     amdgpu_set_dpm_forced_performance_level+0x129/0x330 [amdgpu]
+                        */
+                       mutex_lock(&adev->pm.mutex);
+                       ret = ((adev)->powerplay.pp_funcs->set_powergating_by_smu(
+                               (adev)->powerplay.pp_handle, block_type, gate));
+                       mutex_unlock(&adev->pm.mutex);
                }
                break;
+       case AMD_IP_BLOCK_TYPE_GFX:
+       case AMD_IP_BLOCK_TYPE_VCN:
+       case AMD_IP_BLOCK_TYPE_SDMA:
+               if (swsmu)
+                       ret = smu_dpm_set_power_gate(&adev->smu, block_type, gate);
+               else if (adev->powerplay.pp_funcs &&
+                        adev->powerplay.pp_funcs->set_powergating_by_smu)
+                       ret = ((adev)->powerplay.pp_funcs->set_powergating_by_smu(
+                               (adev)->powerplay.pp_handle, block_type, gate));
+               break;
        case AMD_IP_BLOCK_TYPE_JPEG:
                if (swsmu)
                        ret = smu_dpm_set_power_gate(&adev->smu, block_type, gate);
@@ -970,12 +1001,9 @@ int amdgpu_dpm_set_powergating_by_smu(struct amdgpu_device *adev, uint32_t block
        case AMD_IP_BLOCK_TYPE_GMC:
        case AMD_IP_BLOCK_TYPE_ACP:
                if (adev->powerplay.pp_funcs &&
-                   adev->powerplay.pp_funcs->set_powergating_by_smu) {
-                       mutex_lock(&adev->pm.mutex);
+                   adev->powerplay.pp_funcs->set_powergating_by_smu)
                        ret = ((adev)->powerplay.pp_funcs->set_powergating_by_smu(
                                (adev)->powerplay.pp_handle, block_type, gate));
-                       mutex_unlock(&adev->pm.mutex);
-               }
                break;
        default:
                break;