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author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-02-06 11:27:48 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-02-06 11:27:48 -0800 |
commit | 68c5735eaa5e680e701c9a2d1e3c7880bdf5ab66 (patch) | |
tree | 4f584693638bf257b66a1646cc30d823cacc0a58 /Documentation/media/uapi/dvb/dmx-reqbufs.rst | |
parent | 2246edfaf88dc368e8671b04afd54412625df60a (diff) | |
parent | 273caa260035c03d89ad63d72d8cd3d9e5c5e3f1 (diff) |
Merge tag 'media/v4.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull media updates from Mauro Carvalho Chehab:
- videobuf2 was moved to a media/common dir, as it is now used by the
DVB subsystem too
- Digital TV core memory mapped support interface
- new sensor driver: ov7740
- several improvements at ddbridge driver
- new V4L2 driver: IPU3 CIO2 CSI-2 receiver unit, found on some Intel
SoCs
- new tuner driver: tda18250
- finally got rid of all LIRC staging drivers
- as we don't have old lirc drivers anymore, restruct the lirc device
code
- add support for UVC metadata
- add a new staging driver for NVIDIA Tegra Video Decoder Engine
- DVB kAPI headers moved to include/media
- synchronize the kAPI and uAPI for the DVB subsystem, removing the gap
for non-legacy APIs
- reduce the kAPI gap for V4L2
- lots of other driver enhancements, cleanups, etc.
* tag 'media/v4.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (407 commits)
media: v4l2-compat-ioctl32.c: make ctrl_is_pointer work for subdevs
media: v4l2-compat-ioctl32.c: refactor compat ioctl32 logic
media: v4l2-compat-ioctl32.c: don't copy back the result for certain errors
media: v4l2-compat-ioctl32.c: drop pr_info for unknown buffer type
media: v4l2-compat-ioctl32.c: copy clip list in put_v4l2_window32
media: v4l2-compat-ioctl32.c: fix ctrl_is_pointer
media: v4l2-compat-ioctl32.c: copy m.userptr in put_v4l2_plane32
media: v4l2-compat-ioctl32.c: avoid sizeof(type)
media: v4l2-compat-ioctl32.c: move 'helper' functions to __get/put_v4l2_format32
media: v4l2-compat-ioctl32.c: fix the indentation
media: v4l2-compat-ioctl32.c: add missing VIDIOC_PREPARE_BUF
media: v4l2-ioctl.c: don't copy back the result for -ENOTTY
media: v4l2-ioctl.c: use check_fmt for enum/g/s/try_fmt
media: vivid: fix module load error when enabling fb and no_error_inj=1
media: dvb_demux: improve debug messages
media: dvb_demux: Better handle discontinuity errors
media: cxusb, dib0700: ignore XC2028_I2C_FLUSH
media: ts2020: avoid integer overflows on 32 bit machines
media: i2c: ov7740: use gpio/consumer.h instead of gpio.h
media: entity: Add a nop variant of media_entity_cleanup
...
Diffstat (limited to 'Documentation/media/uapi/dvb/dmx-reqbufs.rst')
-rw-r--r-- | Documentation/media/uapi/dvb/dmx-reqbufs.rst | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/Documentation/media/uapi/dvb/dmx-reqbufs.rst b/Documentation/media/uapi/dvb/dmx-reqbufs.rst new file mode 100644 index 000000000000..14b80d60bf35 --- /dev/null +++ b/Documentation/media/uapi/dvb/dmx-reqbufs.rst @@ -0,0 +1,74 @@ +.. _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. |