drm/amd/pm: fix the deadlock issue observed on SI

The adev->pm.mutx is already held at the beginning of
amdgpu_dpm_compute_clocks/amdgpu_dpm_enable_uvd/amdgpu_dpm_enable_vce.
But on their calling path, amdgpu_display_bandwidth_update will be
called and thus its sub functions amdgpu_dpm_get_sclk/mclk. They
will then try to acquire the same adev->pm.mutex and deadlock will
occur.

By placing amdgpu_display_bandwidth_update outside of adev->pm.mutex
protection(considering logically they do not need such protection) and
restructuring the call flow accordingly, we can eliminate the deadlock
issue. This comes with no real logics change.

Fixes: 3712e7a ("drm/amd/pm: unified lock protections in amdgpu_dpm.c")
Reported-by: Paul Menzel <[email protected]>
Reported-by: Arthur Marsh <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/
BugLink: https://gitlab.freedesktop.org/drm/amd/-/issues/1957
Signed-off-by: Evan Quan <[email protected]>
Reviewed-by: Lijo Lazar <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Evan Quan

drivers/gpu/drm/amd/pm/amdgpu_dpm.c

@@ -427,13 +427,23 @@ int amdgpu_dpm_read_sensor(struct amdgpu_device *adev, enum amd_pp_sensors senso
 void amdgpu_dpm_compute_clocks(struct amdgpu_device *adev)
 {
 	const struct amd_pm_funcs *pp_funcs = adev->powerplay.pp_funcs;
+	int i;
 
 	if (!adev->pm.dpm_enabled)
 		return;
 
 	if (!pp_funcs->pm_compute_clocks)
 		return;
 
+	if (adev->mode_info.num_crtc)
+		amdgpu_display_bandwidth_update(adev);
+
+	for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
+		struct amdgpu_ring *ring = adev->rings[i];
+		if (ring && ring->sched.ready)
+			amdgpu_fence_wait_empty(ring);
+	}
+
 	mutex_lock(&adev->pm.mutex);
 	pp_funcs->pm_compute_clocks(adev->powerplay.pp_handle);
 	mutex_unlock(&adev->pm.mutex);
@@ -443,6 +453,20 @@ void amdgpu_dpm_enable_uvd(struct amdgpu_device *adev, bool enable)
 {
 	int ret = 0;
 
+	if (adev->family == AMDGPU_FAMILY_SI) {
+		mutex_lock(&adev->pm.mutex);
+		if (enable) {
+			adev->pm.dpm.uvd_active = true;
+			adev->pm.dpm.state = POWER_STATE_TYPE_INTERNAL_UVD;
+		} else {
+			adev->pm.dpm.uvd_active = false;
+		}
+		mutex_unlock(&adev->pm.mutex);
+
+		amdgpu_dpm_compute_clocks(adev);
+		return;
+	}
+
 	ret = amdgpu_dpm_set_powergating_by_smu(adev, AMD_IP_BLOCK_TYPE_UVD, !enable);
 	if (ret)
 		DRM_ERROR("Dpm %s uvd failed, ret = %d. \n",
@@ -453,6 +477,21 @@ void amdgpu_dpm_enable_vce(struct amdgpu_device *adev, bool enable)
 {
 	int ret = 0;
 
+	if (adev->family == AMDGPU_FAMILY_SI) {
+		mutex_lock(&adev->pm.mutex);
+		if (enable) {
+			adev->pm.dpm.vce_active = true;
+			/* XXX select vce level based on ring/task */
+			adev->pm.dpm.vce_level = AMD_VCE_LEVEL_AC_ALL;
+		} else {
+			adev->pm.dpm.vce_active = false;
+		}
+		mutex_unlock(&adev->pm.mutex);
+
+		amdgpu_dpm_compute_clocks(adev);
+		return;
+	}
+
 	ret = amdgpu_dpm_set_powergating_by_smu(adev, AMD_IP_BLOCK_TYPE_VCE, !enable);
 	if (ret)
 		DRM_ERROR("Dpm %s vce failed, ret = %d. \n",

drivers/gpu/drm/amd/pm/legacy-dpm/legacy_dpm.c

@@ -1028,16 +1028,6 @@ static int amdgpu_dpm_change_power_state_locked(struct amdgpu_device *adev)
 void amdgpu_legacy_dpm_compute_clocks(void *handle)
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
-	int i = 0;
-
-	if (adev->mode_info.num_crtc)
-		amdgpu_display_bandwidth_update(adev);
-
-	for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
-		struct amdgpu_ring *ring = adev->rings[i];
-		if (ring && ring->sched.ready)
-			amdgpu_fence_wait_empty(ring);
-	}
 
 	amdgpu_dpm_get_active_displays(adev);
 

drivers/gpu/drm/amd/pm/legacy-dpm/si_dpm.c

@@ -3892,40 +3892,6 @@ static int si_set_boot_state(struct amdgpu_device *adev)
 }
 #endif
 
-static int si_set_powergating_by_smu(void *handle,
-				     uint32_t block_type,
-				     bool gate)
-{
-	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
-
-	switch (block_type) {
-	case AMD_IP_BLOCK_TYPE_UVD:
-		if (!gate) {
-			adev->pm.dpm.uvd_active = true;
-			adev->pm.dpm.state = POWER_STATE_TYPE_INTERNAL_UVD;
-		} else {
-			adev->pm.dpm.uvd_active = false;
-		}
-
-		amdgpu_legacy_dpm_compute_clocks(handle);
-		break;
-	case AMD_IP_BLOCK_TYPE_VCE:
-		if (!gate) {
-			adev->pm.dpm.vce_active = true;
-			/* XXX select vce level based on ring/task */
-			adev->pm.dpm.vce_level = AMD_VCE_LEVEL_AC_ALL;
-		} else {
-			adev->pm.dpm.vce_active = false;
-		}
-
-		amdgpu_legacy_dpm_compute_clocks(handle);
-		break;
-	default:
-		break;
-	}
-	return 0;
-}
-
 static int si_set_sw_state(struct amdgpu_device *adev)
 {
 	return (amdgpu_si_send_msg_to_smc(adev, PPSMC_MSG_SwitchToSwState) == PPSMC_Result_OK) ?
@@ -8125,7 +8091,6 @@ static const struct amd_pm_funcs si_dpm_funcs = {
 	.print_power_state = &si_dpm_print_power_state,
 	.debugfs_print_current_performance_level = &si_dpm_debugfs_print_current_performance_level,
 	.force_performance_level = &si_dpm_force_performance_level,
-	.set_powergating_by_smu = &si_set_powergating_by_smu,
 	.vblank_too_short = &si_dpm_vblank_too_short,
 	.set_fan_control_mode = &si_dpm_set_fan_control_mode,
 	.get_fan_control_mode = &si_dpm_get_fan_control_mode,

drivers/gpu/drm/amd/pm/powerplay/amd_powerplay.c

@@ -1487,16 +1487,6 @@ static void pp_pm_compute_clocks(void *handle)
 {
 	struct pp_hwmgr *hwmgr = handle;
 	struct amdgpu_device *adev = hwmgr->adev;
-	int i = 0;
-
-	if (adev->mode_info.num_crtc)
-		amdgpu_display_bandwidth_update(adev);
-
-	for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
-		struct amdgpu_ring *ring = adev->rings[i];
-		if (ring && ring->sched.ready)
-			amdgpu_fence_wait_empty(ring);
-	}
 
 	if (!amdgpu_device_has_dc_support(adev)) {
 		amdgpu_dpm_get_active_displays(adev);