media: mc: add manual request completion

By default when the last request object is completed, the whole
request completes as well.

But sometimes you want to manually complete a request in a driver,
so add a manual complete mode for this.

In req_queue the driver marks the request for manual completion by
calling media_request_mark_manual_completion, and when the driver
wants to manually complete the request it calls
media_request_manual_complete().

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/mc/mc-request.c

@@ -54,6 +54,7 @@ static void media_request_clean(struct media_request *req)
 	req->access_count = 0;
 	WARN_ON(req->num_incomplete_objects);
 	req->num_incomplete_objects = 0;
+	req->manual_completion = false;
 	wake_up_interruptible_all(&req->poll_wait);
 }
 
@@ -313,6 +314,7 @@ int media_request_alloc(struct media_device *mdev, int *alloc_fd)
 	req->mdev = mdev;
 	req->state = MEDIA_REQUEST_STATE_IDLE;
 	req->num_incomplete_objects = 0;
+	req->manual_completion = false;
 	kref_init(&req->kref);
 	INIT_LIST_HEAD(&req->objects);
 	spin_lock_init(&req->lock);
@@ -459,7 +461,7 @@ void media_request_object_unbind(struct media_request_object *obj)
 
 	req->num_incomplete_objects--;
 	if (req->state == MEDIA_REQUEST_STATE_QUEUED &&
-	    !req->num_incomplete_objects) {
+	    !req->num_incomplete_objects && !req->manual_completion) {
 		req->state = MEDIA_REQUEST_STATE_COMPLETE;
 		completed = true;
 		wake_up_interruptible_all(&req->poll_wait);
@@ -488,7 +490,7 @@ void media_request_object_complete(struct media_request_object *obj)
 	    WARN_ON(req->state != MEDIA_REQUEST_STATE_QUEUED))
 		goto unlock;
 
-	if (!--req->num_incomplete_objects) {
+	if (!--req->num_incomplete_objects && !req->manual_completion) {
 		req->state = MEDIA_REQUEST_STATE_COMPLETE;
 		wake_up_interruptible_all(&req->poll_wait);
 		completed = true;
@@ -499,3 +501,35 @@ unlock:
 		media_request_put(req);
 }
 EXPORT_SYMBOL_GPL(media_request_object_complete);
+
+void media_request_manual_complete(struct media_request *req)
+{
+	unsigned long flags;
+	bool completed = false;
+
+	if (WARN_ON(!req))
+		return;
+	if (WARN_ON(!req->manual_completion))
+		return;
+
+	spin_lock_irqsave(&req->lock, flags);
+	if (WARN_ON(req->state != MEDIA_REQUEST_STATE_QUEUED))
+		goto unlock;
+
+	req->manual_completion = false;
+	/*
+	 * It is expected that all other objects in this request are
+	 * completed when this function is called. WARN if that is
+	 * not the case.
+	 */
+	if (!WARN_ON(req->num_incomplete_objects)) {
+		req->state = MEDIA_REQUEST_STATE_COMPLETE;
+		wake_up_interruptible_all(&req->poll_wait);
+		completed = true;
+	}
+unlock:
+	spin_unlock_irqrestore(&req->lock, flags);
+	if (completed)
+		media_request_put(req);
+}
+EXPORT_SYMBOL_GPL(media_request_manual_complete);

include/media/media-request.h

@@ -56,6 +56,10 @@ struct media_request_object;
  * @access_count: count the number of request accesses that are in progress
  * @objects: List of @struct media_request_object request objects
  * @num_incomplete_objects: The number of incomplete objects in the request
+ * @manual_completion: if true, then the request won't be marked as completed
+ * when @num_incomplete_objects reaches 0. Call media_request_manual_complete()
+ * to set this field to false and complete the request
+ * if @num_incomplete_objects == 0.
  * @poll_wait: Wait queue for poll
  * @lock: Serializes access to this struct
  */
@@ -68,6 +72,7 @@ struct media_request {
 	unsigned int access_count;
 	struct list_head objects;
 	unsigned int num_incomplete_objects;
+	bool manual_completion;
 	wait_queue_head_t poll_wait;
 	spinlock_t lock;
 };
@@ -218,6 +223,35 @@ media_request_get_by_fd(struct media_device *mdev, int request_fd);
 int media_request_alloc(struct media_device *mdev,
 			int *alloc_fd);
 
+/**
+ * media_request_mark_manual_completion - Set manual_completion to true
+ *
+ * @req: The request
+ *
+ * Mark that the request has to be manually completed by calling
+ * media_request_manual_complete().
+ *
+ * This function should be called in the req_queue callback.
+ */
+static inline void
+media_request_mark_manual_completion(struct media_request *req)
+{
+	req->manual_completion = true;
+}
+
+/**
+ * media_request_manual_complete - Set manual_completion to false
+ *
+ * @req: The request
+ *
+ * Set @manual_completion to false, and if @num_incomplete_objects
+ * is 0, then mark the request as completed.
+ *
+ * If there are still incomplete objects in the request, then
+ * WARN for that since that suggests a driver error.
+ */
+void media_request_manual_complete(struct media_request *req);
+
 #else
 
 static inline void media_request_get(struct media_request *req)
@@ -336,7 +370,7 @@ void media_request_object_init(struct media_request_object *obj);
  * @req: The media request
  * @ops: The object ops for this object
  * @priv: A driver-specific priv pointer associated with this object
- * @is_buffer: Set to true if the object a buffer object.
+ * @is_buffer: Set to true if the object is a buffer object.
  * @obj: The object
  *
  * Bind this object to the request and set the ops and priv values of