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authorLinus Torvalds <torvalds@linux-foundation.org>2018-02-06 11:27:48 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-06 11:27:48 -0800
commit68c5735eaa5e680e701c9a2d1e3c7880bdf5ab66 (patch)
tree4f584693638bf257b66a1646cc30d823cacc0a58 /Documentation/media/uapi/dvb/dmx-qbuf.rst
parent2246edfaf88dc368e8671b04afd54412625df60a (diff)
parent273caa260035c03d89ad63d72d8cd3d9e5c5e3f1 (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 ...
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+.. _DMX_QBUF:
+
+*************************
+ioctl DMX_QBUF, DMX_DQBUF
+*************************
+
+Name
+====
+
+DMX_QBUF - DMX_DQBUF - Exchange a buffer with the driver
+
+.. warning:: this API is still experimental
+
+
+Synopsis
+========
+
+.. c:function:: int ioctl( int fd, DMX_QBUF, struct dmx_buffer *argp )
+ :name: DMX_QBUF
+
+.. c:function:: int ioctl( int fd, DMX_DQBUF, struct dmx_buffer *argp )
+ :name: DMX_DQBUF
+
+
+Arguments
+=========
+
+``fd``
+ File descriptor returned by :ref:`open() <dmx_fopen>`.
+
+``argp``
+ Pointer to struct :c:type:`dmx_buffer`.
+
+
+Description
+===========
+
+Applications call the ``DMX_QBUF`` ioctl to enqueue an empty
+(capturing) or filled (output) buffer in the driver's incoming queue.
+The semantics depend on the selected I/O method.
+
+To enqueue a buffer applications set the ``index`` field. Valid index
+numbers range from zero to the number of buffers allocated with
+:ref:`DMX_REQBUFS` (struct :c:type:`dmx_requestbuffers` ``count``) minus
+one. The contents of the struct :c:type:`dmx_buffer` returned
+by a :ref:`DMX_QUERYBUF` ioctl will do as well.
+
+When ``DMX_QBUF`` is called with a pointer to this structure, it locks the
+memory pages of the buffer in physical memory, so they cannot be swapped
+out to disk. Buffers remain locked until dequeued, until the
+the device is closed.
+
+Applications call the ``DMX_DQBUF`` ioctl to dequeue a filled
+(capturing) buffer from the driver's outgoing queue. They just set the ``reserved`` field array to zero. When ``DMX_DQBUF`` is called with a
+pointer to this structure, the driver fills the remaining fields or
+returns an error code.
+
+By default ``DMX_DQBUF`` blocks when no buffer is in the outgoing
+queue. When the ``O_NONBLOCK`` flag was given to the
+:ref:`open() <dmx_fopen>` function, ``DMX_DQBUF`` returns
+immediately with an ``EAGAIN`` error code when no buffer is available.
+
+The struct :c:type:`dmx_buffer` structure is specified in
+:ref:`buffer`.
+
+
+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.
+
+EAGAIN
+ Non-blocking I/O has been selected using ``O_NONBLOCK`` and no
+ buffer was in the outgoing queue.
+
+EINVAL
+ The ``index`` is out of bounds, or no buffers have been allocated yet.
+
+EIO
+ ``DMX_DQBUF`` failed due to an internal error. Can also indicate
+ temporary problems like signal loss or CRC errors.