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Diffstat (limited to 'Documentation/media/uapi/dvb/dmx-reqbufs.rst')
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diff --git a/Documentation/media/uapi/dvb/dmx-reqbufs.rst b/Documentation/media/uapi/dvb/dmx-reqbufs.rst deleted file mode 100644 index b302785bf678..000000000000 --- a/Documentation/media/uapi/dvb/dmx-reqbufs.rst +++ /dev/null @@ -1,83 +0,0 @@ -.. Permission is granted to copy, distribute and/or modify this -.. document under the terms of the GNU Free Documentation License, -.. Version 1.1 or any later version published by the Free Software -.. Foundation, with no Invariant Sections, no Front-Cover Texts -.. and no Back-Cover Texts. A copy of the license is included at -.. Documentation/media/uapi/fdl-appendix.rst. -.. -.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections - -.. _DMX_REQBUFS: - -***************** -ioctl DMX_REQBUFS -***************** - -Name -==== - -DMX_REQBUFS - Initiate Memory Mapping and/or DMA buffer I/O - -.. warning:: this API is still experimental - - -Synopsis -======== - -.. c:function:: int ioctl( int fd, DMX_REQBUFS, struct dmx_requestbuffers *argp ) - :name: DMX_REQBUFS - - -Arguments -========= - -``fd`` - File descriptor returned by :ref:`open() <dmx_fopen>`. - -``argp`` - Pointer to struct :c:type:`dmx_requestbuffers`. - -Description -=========== - -This ioctl is used to initiate a memory mapped or DMABUF based demux I/O. - -Memory mapped buffers are located in device memory and must be allocated -with this ioctl before they can be mapped into the application's address -space. User buffers are allocated by applications themselves, and this -ioctl is merely used to switch the driver into user pointer I/O mode and -to setup some internal structures. Similarly, DMABUF buffers are -allocated by applications through a device driver, and this ioctl only -configures the driver into DMABUF I/O mode without performing any direct -allocation. - -To allocate device buffers applications initialize all fields of the -struct :c:type:`dmx_requestbuffers` structure. They set the ``count`` field -to the desired number of buffers, and ``size`` to the size of each -buffer. - -When the ioctl is called with a pointer to this structure, the driver will -attempt to allocate the requested number of buffers and it stores the actual -number allocated in the ``count`` field. The ``count`` can be smaller than the number requested, even zero, when the driver runs out of free memory. A larger -number is also possible when the driver requires more buffers to -function correctly. The actual allocated buffer size can is returned -at ``size``, and can be smaller than what's requested. - -When this I/O method is not supported, the ioctl returns an ``EOPNOTSUPP`` -error code. - -Applications can call :ref:`DMX_REQBUFS` again to change the number of -buffers, however this cannot succeed when any buffers are still mapped. -A ``count`` value of zero frees all buffers, after aborting or finishing -any DMA in progress. - - -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. - -EOPNOTSUPP - The the requested I/O method is not supported. |