drm/msm/gpu: Fix crash during system suspend after unbind

In adreno_unbind, we should clean up gpu device's drvdata to avoid
accessing a stale pointer during system suspend. Also, check for NULL
ptr in both system suspend/resume callbacks.
Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/505075/
Link: https://lore.kernel.org/r/20220928124830.2.I5ee0ac073ccdeb81961e5ec0cce5f741a7207a71@changeidSigned-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/adreno_device.c

@@ -679,6 +679,9 @@ static int adreno_system_suspend(struct device *dev)
 	struct msm_gpu *gpu = dev_to_gpu(dev);
 	int remaining, ret;
 
+	if (!gpu)
+		return 0;
+
 	suspend_scheduler(gpu);
 
 	remaining = wait_event_timeout(gpu->retire_event,
@@ -700,7 +703,12 @@ static int adreno_system_suspend(struct device *dev)
 
 static int adreno_system_resume(struct device *dev)
 {
-	resume_scheduler(dev_to_gpu(dev));
+	struct msm_gpu *gpu = dev_to_gpu(dev);
+
+	if (!gpu)
+		return 0;
+
+	resume_scheduler(gpu);
 	return pm_runtime_force_resume(dev);
 }
 

drivers/gpu/drm/msm/msm_gpu.c

@@ -997,4 +997,6 @@ void msm_gpu_cleanup(struct msm_gpu *gpu)
 	}
 
 	msm_devfreq_cleanup(gpu);
+
+	platform_set_drvdata(gpu->pdev, NULL);
 }

drivers/gpu/drm/msm/msm_gpu.h

@@ -280,6 +280,10 @@ struct msm_gpu {
 static inline struct msm_gpu *dev_to_gpu(struct device *dev)
 {
 	struct adreno_smmu_priv *adreno_smmu = dev_get_drvdata(dev);
+
+	if (!adreno_smmu)
+		return NULL;
+
 	return container_of(adreno_smmu, struct msm_gpu, adreno_smmu);
 }