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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /Documentation/userspace-api/media/mediactl/media-request-ioc-queue.rst | |
parent | Initial commit. (diff) | |
download | linux-upstream/5.10.209.tar.xz linux-upstream/5.10.209.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | Documentation/userspace-api/media/mediactl/media-request-ioc-queue.rst | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/mediactl/media-request-ioc-queue.rst b/Documentation/userspace-api/media/mediactl/media-request-ioc-queue.rst new file mode 100644 index 000000000..04b33db2b --- /dev/null +++ b/Documentation/userspace-api/media/mediactl/media-request-ioc-queue.rst @@ -0,0 +1,77 @@ +.. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later +.. c:namespace:: MC + +.. _media_request_ioc_queue: + +***************************** +ioctl MEDIA_REQUEST_IOC_QUEUE +***************************** + +Name +==== + +MEDIA_REQUEST_IOC_QUEUE - Queue a request + +Synopsis +======== + +.. c:macro:: MEDIA_REQUEST_IOC_QUEUE + +``int ioctl(int request_fd, MEDIA_REQUEST_IOC_QUEUE)`` + +Arguments +========= + +``request_fd`` + File descriptor returned by :ref:`MEDIA_IOC_REQUEST_ALLOC`. + +Description +=========== + +If the media device supports :ref:`requests <media-request-api>`, then +this request ioctl can be used to queue a previously allocated request. + +If the request was successfully queued, then the file descriptor can be +:ref:`polled <request-func-poll>` to wait for the request to complete. + +If the request was already queued before, then ``EBUSY`` is returned. +Other errors can be returned if the contents of the request contained +invalid or inconsistent data, see the next section for a list of +common error codes. On error both the request and driver state are unchanged. + +Once a request is queued, then the driver is required to gracefully handle +errors that occur when the request is applied to the hardware. The +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). ``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 +return an ``ENOENT`` error. + +Return Value +============ + +On success 0 is returned, on error -1 and the ``errno`` variable is set +appropriately. The generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. + +EBUSY + 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 some required + configuration is missing in the request. +ENOMEM + Out of memory when allocating internal data structures for this + request. +EINVAL + The request has invalid data. +EIO + The hardware is in a bad state. To recover, the application needs to + stop streaming to reset the hardware state and then try to restart + streaming. |