media: media-request: EPERM -> EACCES/EBUSY

If requests are not supported by the driver, then return EACCES, not
EPERM.

If you attempt to mix queueing buffers directly and using requests,
then EBUSY is returned instead of EPERM: once a specific queueing mode
has been chosen the queue is 'busy' if you attempt the other mode
(i.e. direct queueing vs via a request).

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/uapi/mediactl/media-request-ioc-queue.rst

@@ -49,7 +49,7 @@ exception is the ``EIO`` error which signals a fatal error that requires
 the application to stop streaming to reset the hardware state.
 
 It is not allowed to mix queuing requests with queuing buffers directly
-(without a request). ``EPERM`` will be returned if the first buffer was
+(without a request). ``EBUSY`` will be returned if the first buffer was
 queued directly and you next try to queue a request, or vice versa.
 
 A request must contain at least one buffer, otherwise this ioctl will
@@ -63,10 +63,9 @@ appropriately. The generic error codes are described at the
 :ref:`Generic Error Codes <gen-errors>` chapter.
 
 EBUSY
-    The request was already queued.
-EPERM
-    The application queued the first buffer directly, but later attempted
-    to use a request. It is not permitted to mix the two APIs.
+    The request was already queued or the application queued the first
+    buffer directly, but later attempted to use a request. It is not permitted
+    to mix the two APIs.
 ENOENT
     The request did not contain any buffers. All requests are required
     to have at least one buffer. This can also be returned if required

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

@@ -64,7 +64,7 @@ request cannot be modified anymore.
 .. caution::
    For :ref:`memory-to-memory devices <codec>` 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 ``EPERM`` error.
+   to a request will result in an ``EACCES`` error.
 
 If the request contains parameters for multiple entities, individual drivers may
 synchronize so the requested pipeline's topology is applied before the buffers
@@ -77,7 +77,7 @@ perfect atomicity may not be possible due to hardware limitations.
    whichever method is used first locks this in place until
    :ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` is called or the device is
    :ref:`closed <func-close>`. Attempts to directly queue a buffer when earlier
-   a buffer was queued via a request or vice versa will result in an ``EPERM``
+   a buffer was queued via a request or vice versa will result in an ``EBUSY``
    error.
 
 Controls can still be set without a request and are applied immediately,

Documentation/media/uapi/v4l/buffer.rst

@@ -314,7 +314,7 @@ struct v4l2_buffer
 	:ref:`ioctl VIDIOC_QBUF <VIDIOC_QBUF>` and ignored by other ioctls.
 	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 ``EPERM`` will be returned.
+	If the device does not support requests, then ``EACCES`` 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-g-ext-ctrls.rst

@@ -100,7 +100,7 @@ file descriptor and ``which`` is set to ``V4L2_CTRL_WHICH_REQUEST_VAL``,
 then the controls are not applied immediately when calling
 :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`, but instead are applied by
 the driver for the buffer associated with the same request.
-If the device does not support requests, then ``EPERM`` will be returned.
+If the device does not support requests, then ``EACCES`` will be returned.
 If requests are supported but an invalid request file descriptor is given,
 then ``EINVAL`` will be returned.
 
@@ -233,7 +233,7 @@ still cause this situation.
 	these controls have to be retrieved from a request or tried/set for
 	a request. In the latter case the ``request_fd`` field contains the
 	file descriptor of the request that should be used. If the device
-	does not support requests, then ``EPERM`` will be returned.
+	does not support requests, then ``EACCES`` will be returned.
 
 	.. note::
 
@@ -299,7 +299,7 @@ still cause this situation.
       - ``request_fd``
       - File descriptor of the request to be used by this operation. Only
 	valid if ``which`` is set to ``V4L2_CTRL_WHICH_REQUEST_VAL``.
-	If the device does not support requests, then ``EPERM`` will be returned.
+	If the device does not support requests, then ``EACCES`` will be returned.
 	If requests are supported but an invalid request file descriptor is
 	given, then ``EINVAL`` will be returned.
     * - __u32
@@ -408,6 +408,5 @@ EACCES
     control, or to get a control from a request that has not yet been
     completed.
 
-EPERM
-    The ``which`` field was set to ``V4L2_CTRL_WHICH_REQUEST_VAL`` but the
+    Or the ``which`` field was set to ``V4L2_CTRL_WHICH_REQUEST_VAL`` but the
     device does not support requests.

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

@@ -104,18 +104,18 @@ in use. Setting it means that the buffer will not be passed to the driver
 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 ``EPERM`` will be returned.
+If the device does not support requests, then ``EACCES`` will be returned.
 If requests are supported but an invalid request file descriptor is given,
 then ``EINVAL`` will be returned.
 
 .. caution::
    It is not allowed to mix queuing requests with queuing buffers directly.
-   ``EPERM`` will be returned if the first buffer was queued directly and
+   ``EBUSY`` will be returned if the first buffer was queued directly and
    then the application tries to queue a request, or vice versa.
 
    For :ref:`memory-to-memory devices <codec>` 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 ``EPERM`` error.
+   to specify this for a capture buffer will result in an ``EACCES`` error.
 
 Applications call the ``VIDIOC_DQBUF`` ioctl to dequeue a filled
 (capturing) or displayed (output) buffer from the driver's outgoing
@@ -175,9 +175,11 @@ EPIPE
     codecs if a buffer with the ``V4L2_BUF_FLAG_LAST`` was already
     dequeued and no new buffers are expected to become available.
 
-EPERM
+EACCES
     The ``V4L2_BUF_FLAG_REQUEST_FD`` flag was set but the device does not
-    support requests. Or the first buffer was queued via a request, but
-    the application now tries to queue it directly, or vice versa (it is
-    not permitted to mix the two APIs). Or an attempt is made to queue a
-    CAPTURE buffer to a request for a :ref:`memory-to-memory device <codec>`.
+    support requests for the given buffer type.
+
+EBUSY
+    The first buffer was queued via a request, but the application now tries
+    to queue it directly, or vice versa (it is not permitted to mix the two
+    APIs).

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

@@ -1495,7 +1495,7 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb,
 	    (!req && vb->state != VB2_BUF_STATE_IN_REQUEST &&
 	     q->uses_requests)) {
 		dprintk(1, "queue in wrong mode (qbuf vs requests)\n");
-		return -EPERM;
+		return -EBUSY;
 	}
 
 	if (req) {

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

@@ -381,12 +381,15 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
 	if (!(b->flags & V4L2_BUF_FLAG_REQUEST_FD)) {
 		if (q->uses_requests) {
 			dprintk(1, "%s: queue uses requests\n", opname);
-			return -EPERM;
+			return -EBUSY;
 		}
 		return 0;
-	} else if (q->uses_qbuf || !q->supports_requests) {
+	} else if (!q->supports_requests) {
+		dprintk(1, "%s: queue does not support requests\n", opname);
+		return -EACCES;
+	} else if (q->uses_qbuf) {
 		dprintk(1, "%s: queue does not use requests\n", opname);
-		return -EPERM;
+		return -EBUSY;
 	}
 
 	/*

drivers/media/media-request.c

@@ -249,7 +249,7 @@ media_request_get_by_fd(struct media_device *mdev, int request_fd)
 
 	if (!mdev || !mdev->ops ||
 	    !mdev->ops->req_validate || !mdev->ops->req_queue)
-		return ERR_PTR(-EPERM);
+		return ERR_PTR(-EACCES);
 
 	filp = fget(request_fd);
 	if (!filp)
@@ -405,7 +405,7 @@ int media_request_object_bind(struct media_request *req,
 	int ret = -EBUSY;
 
 	if (WARN_ON(!ops->release))
-		return -EPERM;
+		return -EACCES;
 
 	spin_lock_irqsave(&req->lock, flags);
 

include/media/media-request.h

@@ -198,7 +198,7 @@ void media_request_put(struct media_request *req);
  * Get the request represented by @request_fd that is owned
  * by the media device.
  *
- * Return a -EPERM error pointer if requests are not supported
+ * Return a -EACCES 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
@@ -231,7 +231,7 @@ static inline void media_request_put(struct media_request *req)
 static inline struct media_request *
 media_request_get_by_fd(struct media_device *mdev, int request_fd)
 {
-	return ERR_PTR(-EPERM);
+	return ERR_PTR(-EACCES);
 }
 
 #endif