drm/msm/disp: Export helper for capturing snapshot

We'll re-use this for debugfs.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20211215174524.1742389-3-robdclark@gmail.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/disp/msm_disp_snapshot.c

@@ -28,29 +28,42 @@ static ssize_t __maybe_unused disp_devcoredump_read(char *buffer, loff_t offset,
 	return count - iter.remain;
 }
 
-static void _msm_disp_snapshot_work(struct kthread_work *work)
+struct msm_disp_state *
+msm_disp_snapshot_state_sync(struct msm_kms *kms)
 {
-	struct msm_kms *kms = container_of(work, struct msm_kms, dump_work);
 	struct drm_device *drm_dev = kms->dev;
 	struct msm_disp_state *disp_state;
-	struct drm_printer p;
+
+	WARN_ON(!mutex_is_locked(&kms->dump_mutex));
 
 	disp_state = kzalloc(sizeof(struct msm_disp_state), GFP_KERNEL);
 	if (!disp_state)
-		return;
+		return ERR_PTR(-ENOMEM);
 
 	disp_state->dev = drm_dev->dev;
 	disp_state->drm_dev = drm_dev;
 
 	INIT_LIST_HEAD(&disp_state->blocks);
 
-	/* Serialize dumping here */
-	mutex_lock(&kms->dump_mutex);
-
 	msm_disp_snapshot_capture_state(disp_state);
 
+	return disp_state;
+}
+
+static void _msm_disp_snapshot_work(struct kthread_work *work)
+{
+	struct msm_kms *kms = container_of(work, struct msm_kms, dump_work);
+	struct msm_disp_state *disp_state;
+	struct drm_printer p;
+
+	/* Serialize dumping here */
+	mutex_lock(&kms->dump_mutex);
+	disp_state = msm_disp_snapshot_state_sync(kms);
 	mutex_unlock(&kms->dump_mutex);
 
+	if (IS_ERR(disp_state))
+		return;
+
 	if (MSM_DISP_SNAPSHOT_DUMP_IN_CONSOLE) {
 		p = drm_info_printer(disp_state->drm_dev->dev);
 		msm_disp_state_print(disp_state, &p);

drivers/gpu/drm/msm/disp/msm_disp_snapshot.h

@@ -84,6 +84,16 @@ int msm_disp_snapshot_init(struct drm_device *drm_dev);
  */
 void msm_disp_snapshot_destroy(struct drm_device *drm_dev);
 
+/**
+ * msm_disp_snapshot_state_sync - synchronously snapshot display state
+ * @kms:  the kms object
+ *
+ * Returns state or error
+ *
+ * Must be called with &kms->dump_mutex held
+ */
+struct msm_disp_state *msm_disp_snapshot_state_sync(struct msm_kms *kms);
+
 /**
  * msm_disp_snapshot_state - trigger to dump the display snapshot
  * @drm_dev:	handle to drm device