[PATCH] drm/amd/powerplay: fix null pointer dereference around dpm state relates

[Evan Quan]

DPM state relates are not supported on the new SW SMU ASICs. But still
it's not OK to trigger null pointer dereference on accessing them.

Change-Id: I368d108fbea438ed5d9e3b849d006ddd5308052b
Signed-off-by: Evan Quan <evan.quan at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c     | 18 +++++++++++++-----
 drivers/gpu/drm/amd/powerplay/amdgpu_smu.c |  3 ++-
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
index 304626b21a8c..61312b02b5c7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
@@ -209,12 +209,16 @@ static ssize_t amdgpu_get_dpm_state(struct device *dev,
 	struct amdgpu_device *adev = ddev->dev_private;
 	enum amd_pm_state_type pm;
 
-	if (is_support_sw_smu(adev) && adev->smu.ppt_funcs->get_current_power_state)
-		pm = amdgpu_smu_get_current_power_state(adev);
-	else if (adev->powerplay.pp_funcs->get_current_power_state)
+	if (is_support_sw_smu(adev)) {
+		if (adev->smu.ppt_funcs->get_current_power_state)
+			pm = amdgpu_smu_get_current_power_state(adev);
+		else
+			pm = adev->pm.dpm.user_state;
+	} else if (adev->powerplay.pp_funcs->get_current_power_state) {
 		pm = amdgpu_dpm_get_current_power_state(adev);
-	else
+	} else {
 		pm = adev->pm.dpm.user_state;
+	}
 
 	return snprintf(buf, PAGE_SIZE, "%s\n",
 			(pm == POWER_STATE_TYPE_BATTERY) ? "battery" :
@@ -241,7 +245,11 @@ static ssize_t amdgpu_set_dpm_state(struct device *dev,
 		goto fail;
 	}
 
-	if (adev->powerplay.pp_funcs->dispatch_tasks) {
+	if (is_support_sw_smu(adev)) {
+		mutex_lock(&adev->pm.mutex);
+		adev->pm.dpm.user_state = state;
+		mutex_unlock(&adev->pm.mutex);
+	} else if (adev->powerplay.pp_funcs->dispatch_tasks) {
 		amdgpu_dpm_dispatch_task(adev, AMD_PP_TASK_ENABLE_USER_STATE, &state);
 	} else {
 		mutex_lock(&adev->pm.mutex);
diff --git a/drivers/gpu/drm/amd/powerplay/amdgpu_smu.c b/drivers/gpu/drm/amd/powerplay/amdgpu_smu.c
index a5079b93caa3..3ecd67e6e65c 100644
--- a/drivers/gpu/drm/amd/powerplay/amdgpu_smu.c
+++ b/drivers/gpu/drm/amd/powerplay/amdgpu_smu.c
@@ -304,7 +304,8 @@ int smu_get_power_num_states(struct smu_context *smu,
 
 	/* not support power state */
 	memset(state_info, 0, sizeof(struct pp_states_info));
-	state_info->nums = 0;
+	state_info->nums = 1;
+	state_info->states[0] = POWER_STATE_TYPE_DEFAULT;
 
 	return 0;
 }
-- 
2.22.0