[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>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/media/video/videobuf2-core.c b/drivers/media/video/videobuf2-core.c
index 60e7bc78d190..ed38eb748357 100644
--- 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);