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author | Jiri Kosina <jkosina@suse.cz> | 2018-11-06 13:57:02 +0100 |
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committer | Jiri Kosina <jkosina@suse.cz> | 2018-11-06 13:57:02 +0100 |
commit | 0c7244209588630a9b45e52490ef1390e04499a6 (patch) | |
tree | d60f5610f9b36ff05ed5202396c811628bacdb61 /Documentation/media/uapi/mediactl/request-func-ioctl.rst | |
parent | HID: i2c-hid: add Direkt-Tek DTLAPY133-1 to descriptor override (diff) | |
parent | Merge tag 'platform-drivers-x86-v4.20-1' of git://git.infradead.org/linux-platform-drivers-x86 (diff) | |
download | linux-dev-0c7244209588630a9b45e52490ef1390e04499a6.tar.xz linux-dev-0c7244209588630a9b45e52490ef1390e04499a6.zip |
Merge branch 'master' into for-4.20/upstream-fixes
Pull in a merge commit that brought in 3b692c55e58d ("HID: asus: only
support backlight when it's not driven by WMI") so that fixup could be
applied on top of it.
Diffstat (limited to 'Documentation/media/uapi/mediactl/request-func-ioctl.rst')
-rw-r--r-- | Documentation/media/uapi/mediactl/request-func-ioctl.rst | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/Documentation/media/uapi/mediactl/request-func-ioctl.rst b/Documentation/media/uapi/mediactl/request-func-ioctl.rst new file mode 100644 index 000000000000..ff7b072a6999 --- /dev/null +++ b/Documentation/media/uapi/mediactl/request-func-ioctl.rst @@ -0,0 +1,67 @@ +.. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections + +.. _request-func-ioctl: + +*************** +request ioctl() +*************** + +Name +==== + +request-ioctl - Control a request file descriptor + + +Synopsis +======== + +.. code-block:: c + + #include <sys/ioctl.h> + + +.. c:function:: int ioctl( int fd, int cmd, void *argp ) + :name: req-ioctl + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`MEDIA_IOC_REQUEST_ALLOC`. + +``cmd`` + The request ioctl command code as defined in the media.h header file, for + example :ref:`MEDIA_REQUEST_IOC_QUEUE`. + +``argp`` + Pointer to a request-specific structure. + + +Description +=========== + +The :ref:`ioctl() <request-func-ioctl>` function manipulates request +parameters. The argument ``fd`` must be an open file descriptor. + +The ioctl ``cmd`` code specifies the request function to be called. It +has encoded in it whether the argument is an input, output or read/write +parameter, and the size of the argument ``argp`` in bytes. + +Macros and structures definitions specifying request ioctl commands and +their parameters are located in the media.h header file. All request ioctl +commands, their respective function and parameters are specified in +:ref:`media-user-func`. + + +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. + +Command-specific error codes are listed in the individual command +descriptions. + +When an ioctl that takes an output or read/write parameter fails, the +parameter remains unmodified. |