media: media requests: return EBADR instead of EACCES

If requests are used when they shouldn't, or not used when they should,
then return EBADR (Invalid request descriptor) instead of EACCES.

The reason for this change is that EACCES has more to do with permissions
(not being the owner of the resource), but in this case the request file
descriptor is just wrong for the current mode of the device.

Update the documentation accordingly.

Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/media/uapi/mediactl/request-api.rst

···
 .. caution::
    For :ref:`memory-to-memory devices <mem2mem>` you can use requests only for
    output buffers, not for capture buffers. Attempting to add a capture buffer
-   to a request will result in an ``EACCES`` error.
+   to a request will result in an ``EBADR`` error.
 
 If the request contains configurations for multiple entities, individual drivers
 may synchronize so the requested pipeline's topology is applied before the

Documentation/media/uapi/v4l/buffer.rst

···
 	Applications should not set ``V4L2_BUF_FLAG_REQUEST_FD`` for any ioctls
 	other than :ref:`VIDIOC_QBUF <VIDIOC_QBUF>`.
 
-	If the device does not support requests, then ``EACCES`` will be returned.
+	If the device does not support requests, then ``EBADR`` will be returned.
 	If requests are supported but an invalid request file descriptor is
 	given, then ``EINVAL`` will be returned.
 

Documentation/media/uapi/v4l/vidioc-qbuf.rst

···
 until the request itself is queued. Also, the driver will apply any
 settings associated with the request for this buffer. This field will
 be ignored unless the ``V4L2_BUF_FLAG_REQUEST_FD`` flag is set.
-If the device does not support requests, then ``EACCES`` will be returned.
+If the device does not support requests, then ``EBADR`` will be returned.
 If requests are supported but an invalid request file descriptor is given,
 then ``EINVAL`` will be returned.
 
···
 
    For :ref:`memory-to-memory devices <mem2mem>` you can specify the
    ``request_fd`` only for output buffers, not for capture buffers. Attempting
-   to specify this for a capture buffer will result in an ``EACCES`` error.
+   to specify this for a capture buffer will result in an ``EBADR`` error.
 
 Applications call the ``VIDIOC_DQBUF`` ioctl to dequeue a filled
 (capturing) or displayed (output) buffer from the driver's outgoing
···
     codecs if a buffer with the ``V4L2_BUF_FLAG_LAST`` was already
     dequeued and no new buffers are expected to become available.
 
-EACCES
-    The ``V4L2_BUF_FLAG_REQUEST_FD`` flag was set but the device does not
-    support requests for the given buffer type.
-
 EBADR
-    The ``V4L2_BUF_FLAG_REQUEST_FD`` flag was not set but the device requires
+    The ``V4L2_BUF_FLAG_REQUEST_FD`` flag was set but the device does not
+    support requests for the given buffer type, or
+    the ``V4L2_BUF_FLAG_REQUEST_FD`` flag was not set but the device requires
     that the buffer is part of a request.
 
 EBUSY

drivers/media/common/videobuf2/videobuf2-v4l2.c

···
 		return 0;
 	} else if (!q->supports_requests) {
 		dprintk(1, "%s: queue does not support requests\n", opname);
-		return -EACCES;
+		return -EBADR;
 	} else if (q->uses_qbuf) {
 		dprintk(1, "%s: queue does not use requests\n", opname);
 		return -EBUSY;

drivers/media/media-request.c

···
 
 	if (!mdev || !mdev->ops ||
 	    !mdev->ops->req_validate || !mdev->ops->req_queue)
-		return ERR_PTR(-EACCES);
+		return ERR_PTR(-EBADR);
 
 	filp = fget(request_fd);
 	if (!filp)
···
 	int ret = -EBUSY;
 
 	if (WARN_ON(!ops->release))
-		return -EACCES;
+		return -EBADR;
 
 	spin_lock_irqsave(&req->lock, flags);
 

include/media/media-request.h

···
  * Get the request represented by @request_fd that is owned
  * by the media device.
  *
- * Return a -EACCES error pointer if requests are not supported
+ * Return a -EBADR error pointer if requests are not supported
  * by this driver. Return -EINVAL if the request was not found.
  * Return the pointer to the request if found: the caller will
  * have to call @media_request_put when it finished using the
···
 static inline struct media_request *
 media_request_get_by_fd(struct media_device *mdev, int request_fd)
 {
-	return ERR_PTR(-EACCES);
+	return ERR_PTR(-EBADR);
 }
 
 #endif