media: videobuf2: Replace bufs array by a list

Replacing bufs array by a list allows to remove the 32 buffers
limit per queue.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>

drivers/media/common/videobuf2/videobuf2-core.c

@@ -412,10 +412,6 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
 	struct vb2_buffer *vb;
 	int ret;
 
-	/* Ensure that q->num_buffers+num_buffers is below VB2_MAX_FRAME */
-	num_buffers = min_t(unsigned int, num_buffers,
-			    VB2_MAX_FRAME - q->num_buffers);
-
 	for (buffer = 0; buffer < num_buffers; ++buffer) {
 		/* Allocate vb2 buffer structures */
 		vb = kzalloc(q->buf_struct_size, GFP_KERNEL);
@@ -797,9 +793,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 	/*
 	 * Make sure the requested values and current defaults are sane.
 	 */
-	WARN_ON(q->min_buffers_needed > VB2_MAX_FRAME);
 	num_buffers = max_t(unsigned int, *count, q->min_buffers_needed);
-	num_buffers = min_t(unsigned int, num_buffers, VB2_MAX_FRAME);
 	memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
 	/*
 	 * Set this now to ensure that drivers see the correct q->memory value
@@ -915,11 +909,6 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 	bool no_previous_buffers = !q->num_buffers;
 	int ret;
 
-	if (q->num_buffers == VB2_MAX_FRAME) {
-		dprintk(q, 1, "maximum number of buffers already allocated\n");
-		return -ENOBUFS;
-	}
-
 	if (no_previous_buffers) {
 		if (q->waiting_in_dqbuf && *count) {
 			dprintk(q, 1, "another dup()ped fd is waiting for a buffer\n");
@@ -944,7 +933,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 			return -EINVAL;
 	}
 
-	num_buffers = min(*count, VB2_MAX_FRAME - q->num_buffers);
+	num_buffers = *count;
 
 	if (requested_planes && requested_sizes) {
 		num_planes = requested_planes;
@@ -2444,6 +2433,7 @@ int vb2_core_queue_init(struct vb2_queue *q)
 
 	INIT_LIST_HEAD(&q->queued_list);
 	INIT_LIST_HEAD(&q->done_list);
+	INIT_LIST_HEAD(&q->allocated_bufs);
 	spin_lock_init(&q->done_lock);
 	mutex_init(&q->mmap_lock);
 	init_waitqueue_head(&q->done_wq);

include/media/videobuf2-core.h

@@ -276,6 +276,8 @@ struct vb2_buffer {
 	 * done_entry:		entry on the list that stores all buffers ready
 	 *			to be dequeued to userspace
 	 * vb2_plane:		per-plane information; do not change
+	 * allocated_entry:	entry on the list that stores all buffers allocated
+	 *			for the queue.
 	 */
 	enum vb2_buffer_state	state;
 	unsigned int		synced:1;
@@ -287,6 +289,7 @@ struct vb2_buffer {
 	struct vb2_plane	planes[VB2_MAX_PLANES];
 	struct list_head	queued_entry;
 	struct list_head	done_entry;
+	struct list_head	allocated_entry;
 #ifdef CONFIG_VIDEO_ADV_DEBUG
 	/*
 	 * Counters for how often these buffer-related ops are
@@ -556,7 +559,7 @@ struct vb2_buf_ops {
  * @mmap_lock:	private mutex used when buffers are allocated/freed/mmapped
  * @memory:	current memory type used
  * @dma_dir:	DMA mapping direction.
- * @bufs:	videobuf2 buffer structures
+ * @allocated_bufs: list of buffer allocated for the queue.
  * @num_buffers: number of allocated/used buffers
  * @queued_list: list of buffers currently queued from userspace
  * @queued_count: number of buffers queued and ready for streaming.
@@ -619,7 +622,7 @@ struct vb2_queue {
 	struct mutex			mmap_lock;
 	unsigned int			memory;
 	enum dma_data_direction		dma_dir;
-	struct vb2_buffer		*bufs[VB2_MAX_FRAME];
+	struct list_head		allocated_bufs;
 	unsigned int			num_buffers;
 
 	struct list_head		queued_list;
@@ -1239,8 +1242,12 @@ static inline void vb2_clear_last_buffer_dequeued(struct vb2_queue *q)
 static inline struct vb2_buffer *vb2_get_buffer(struct vb2_queue *q,
 						unsigned int index)
 {
-	if (index < q->num_buffers)
-		return q->bufs[index];
+	struct vb2_buffer *vb;
+
+	list_for_each_entry(vb, &q->allocated_bufs, allocated_entry)
+		if (vb->index == index)
+			return vb;
+
 	return NULL;
 }
 
@@ -1251,7 +1258,7 @@ static inline struct vb2_buffer *vb2_get_buffer(struct vb2_queue *q,
  */
 static inline void vb2_set_buffer(struct vb2_queue *q, struct vb2_buffer *vb)
 {
-	q->bufs[vb->index] = vb;
+	list_add_tail(&vb->allocated_entry, &q->allocated_bufs);
 }
 
 /**
@@ -1261,7 +1268,7 @@ static inline void vb2_set_buffer(struct vb2_queue *q, struct vb2_buffer *vb)
  */
 static inline void vb2_del_buffer(struct vb2_queue *q, struct vb2_buffer *vb)
 {
-	q->bufs[vb->index] = NULL;
+	list_del(&vb->allocated_entry);
 }
 
 /*