[PATCH v6 11/18] media: videobuf2: Be more flexible on the number of queue stored buffers

[Benjamin Gaignard]

Add 'max_allowed_buffers' field in vb2_queue struct to let drivers decide
how many buffers could be stored in a queue.
This request 'bufs' array to be allocated at queue init time and freed
when releasing the queue.
By default VB2_MAX_FRAME remains the limit.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard at collabora.com>
---
 .../media/common/videobuf2/videobuf2-core.c   | 25 +++++++++++++------
 include/media/videobuf2-core.h                |  4 ++-
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 15b583ce0c69..dc7f6b59d237 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -411,7 +411,7 @@ static void init_buffer_cache_hints(struct vb2_queue *q, struct vb2_buffer *vb)
  */
 static bool vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *vb, unsigned int index)
 {
-	if (index < VB2_MAX_FRAME && !q->bufs[index]) {
+	if (index < q->max_allowed_buffers && !q->bufs[index]) {
 		q->bufs[index] = vb;
 		vb->index = index;
 		vb->vb2_queue = q;
@@ -428,7 +428,7 @@ static bool vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *vb, uns
  */
 static void vb2_queue_remove_buffer(struct vb2_queue *q, struct vb2_buffer *vb)
 {
-	if (vb->index < VB2_MAX_FRAME) {
+	if (vb->index < q->max_allowed_buffers) {
 		q->bufs[vb->index] = NULL;
 		vb->vb2_queue = NULL;
 	}
@@ -449,9 +449,9 @@ 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 */
+	/* Ensure that q->num_buffers+num_buffers is below q->max_allowed_buffers */
 	num_buffers = min_t(unsigned int, num_buffers,
-			    VB2_MAX_FRAME - q->num_buffers);
+			    q->max_allowed_buffers - q->num_buffers);
 
 	for (buffer = 0; buffer < num_buffers; ++buffer) {
 		/* Allocate vb2 buffer structures */
@@ -862,9 +862,9 @@ 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);
+	WARN_ON(q->min_buffers_needed > q->max_allowed_buffers);
 	num_buffers = max_t(unsigned int, *count, q->min_buffers_needed);
-	num_buffers = min_t(unsigned int, num_buffers, VB2_MAX_FRAME);
+	num_buffers = min_t(unsigned int, num_buffers, q->max_allowed_buffers);
 	memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
 	/*
 	 * Set this now to ensure that drivers see the correct q->memory value
@@ -980,7 +980,7 @@ 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) {
+	if (q->num_buffers == q->max_allowed_buffers) {
 		dprintk(q, 1, "maximum number of buffers already allocated\n");
 		return -ENOBUFS;
 	}
@@ -1009,7 +1009,7 @@ 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 = min(*count, q->max_allowed_buffers - q->num_buffers);
 
 	if (requested_planes && requested_sizes) {
 		num_planes = requested_planes;
@@ -2519,6 +2519,14 @@ int vb2_core_queue_init(struct vb2_queue *q)
 
 	q->memory = VB2_MEMORY_UNKNOWN;
 
+	if (!q->max_allowed_buffers)
+		q->max_allowed_buffers = VB2_MAX_FRAME;
+
+	/* The maximum is limited by offset cookie encoding pattern */
+	q->max_allowed_buffers = min_t(unsigned int, q->max_allowed_buffers, BUFFER_INDEX_MASK);
+
+	q->bufs = kcalloc(q->max_allowed_buffers, sizeof(*q->bufs), GFP_KERNEL);
+
 	if (q->buf_struct_size == 0)
 		q->buf_struct_size = sizeof(struct vb2_buffer);
 
@@ -2543,6 +2551,7 @@ void vb2_core_queue_release(struct vb2_queue *q)
 	__vb2_queue_cancel(q);
 	mutex_lock(&q->mmap_lock);
 	__vb2_queue_free(q, q->num_buffers);
+	kfree(q->bufs);
 	mutex_unlock(&q->mmap_lock);
 }
 EXPORT_SYMBOL_GPL(vb2_core_queue_release);
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index cd3ff1cd759d..97153c69583f 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -558,6 +558,7 @@ struct vb2_buf_ops {
  * @dma_dir:	DMA mapping direction.
  * @bufs:	videobuf2 buffer structures
  * @num_buffers: number of allocated/used buffers
+ * @max_allowed_buffers: upper limit of number of allocated/used buffers
  * @queued_list: list of buffers currently queued from userspace
  * @queued_count: number of buffers queued and ready for streaming.
  * @owned_by_drv_count: number of buffers owned by the driver
@@ -619,8 +620,9 @@ struct vb2_queue {
 	struct mutex			mmap_lock;
 	unsigned int			memory;
 	enum dma_data_direction		dma_dir;
-	struct vb2_buffer		*bufs[VB2_MAX_FRAME];
+	struct vb2_buffer		**bufs;
 	unsigned int			num_buffers;
+	unsigned int			max_allowed_buffers;
 
 	struct list_head		queued_list;
 	unsigned int			queued_count;
-- 
2.39.2