[media] vb2-core: add support for count == 0 in create_bufs

This also fixes incorrect error handling in create_bufs: the return code
of __vb2_queue_alloc is the number of allocated buffers, and not a
traditional error code.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/video/videobuf2-core.c b/drivers/media/video/videobuf2-core.c
index 60e7bc78d190551e889fb0ce0aad8935d21ad381..ed38eb748357e9b5603495deb95fd736fb165db0 100644 (file)
--- a/drivers/media/video/videobuf2-core.c
+++ b/drivers/media/video/videobuf2-core.c
@@ -669,9 +669,9 @@ static int __create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create
        /* Finally, allocate buffers and video memory */
        ret = __vb2_queue_alloc(q, create->memory, num_buffers,
                                num_planes);
-       if (ret < 0) {
-               dprintk(1, "Memory allocation failed with error: %d\n", ret);
-               return ret;
+       if (ret == 0) {
+               dprintk(1, "Memory allocation failed\n");
+               return -ENOMEM;
        }
 
        allocated_buffers = ret;
@@ -702,7 +702,7 @@ static int __create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create
 
        if (ret < 0) {
                __vb2_queue_free(q, allocated_buffers);
-               return ret;
+               return -ENOMEM;
        }
 
        /*
@@ -726,6 +726,8 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
        int ret = __verify_memory_type(q, create->memory, create->format.type);
 
        create->index = q->num_buffers;
+       if (create->count == 0)
+               return ret != -EBUSY ? ret : 0;
        return ret ? ret : __create_bufs(q, create);
 }
 EXPORT_SYMBOL_GPL(vb2_create_bufs);