diff options
| author | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2016-08-15 17:49:50 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2016-08-22 10:02:29 -0300 |
| commit | b6b6e67824ec0593878afbee5958d80205606210 (patch) | |
| tree | 433e204fb20bf108880513bfe0d67b4e6841e90e /Documentation/media/uapi/v4l | |
| parent | 187594418d37b29d02a22f5d15db51ea4df70957 (diff) | |
[media] docs-rst: better use the .. note:: tag
Change multi-line note tags to be more symetric, e. g. not starting
the text together witht the tag.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Diffstat (limited to 'Documentation/media/uapi/v4l')
36 files changed, 148 insertions, 50 deletions
diff --git a/Documentation/media/uapi/v4l/audio.rst b/Documentation/media/uapi/v4l/audio.rst index 4dd11345866c..b8059fb05372 100644 --- a/Documentation/media/uapi/v4l/audio.rst +++ b/Documentation/media/uapi/v4l/audio.rst @@ -37,7 +37,9 @@ The :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` and :ref:`VIDIOC_G_AUDOUT <VIDIOC_G_AUDOUT>` ioctls report the current audio input and output, respectively. -.. note:: Note that, unlike :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` and +.. note:: + + Note that, unlike :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` and :ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` these ioctls return a structure as :ref:`VIDIOC_ENUMAUDIO` and :ref:`VIDIOC_ENUMAUDOUT <VIDIOC_ENUMAUDOUT>` do, not just an index. diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst index 5deb4a46f992..f75f959b960b 100644 --- a/Documentation/media/uapi/v4l/buffer.rst +++ b/Documentation/media/uapi/v4l/buffer.rst @@ -166,12 +166,15 @@ struct v4l2_buffer output device because the application did not pass new data in time. - .. note:: This may count the frames received e.g. over USB, without + .. note:: + + This may count the frames received e.g. over USB, without taking into account the frames dropped by the remote hardware due to limited compression throughput or bus bandwidth. These devices identify by not enumerating any video standards, see :ref:`standard`. + - .. row 10 - __u32 @@ -299,7 +302,9 @@ struct v4l2_plane ``bytesused`` will be set to the size of the plane (see the ``length`` field of this struct) by the driver. - .. note:: Note that the actual image data starts at ``data_offset`` + .. note:: + + Note that the actual image data starts at ``data_offset`` which may not be 0. - .. row 2 @@ -371,7 +376,9 @@ struct v4l2_plane field when ``type`` refers to a capture stream, applications when it refers to an output stream. - .. note:: That data_offset is included in ``bytesused``. So the + .. note:: + + That data_offset is included in ``bytesused``. So the size of the image in the plane is ``bytesused``-``data_offset`` at offset ``data_offset`` from the start of the plane. diff --git a/Documentation/media/uapi/v4l/crop.rst b/Documentation/media/uapi/v4l/crop.rst index 0913822347af..4622884b06ea 100644 --- a/Documentation/media/uapi/v4l/crop.rst +++ b/Documentation/media/uapi/v4l/crop.rst @@ -15,7 +15,9 @@ offset into a video signal. Applications can use the following API to select an area in the video signal, query the default area and the hardware limits. -.. note:: Despite their name, the :ref:`VIDIOC_CROPCAP <VIDIOC_CROPCAP>`, +.. note:: + + Despite their name, the :ref:`VIDIOC_CROPCAP <VIDIOC_CROPCAP>`, :ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` ioctls apply to input as well as output devices. @@ -38,7 +40,9 @@ support scaling or the :ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` ioctls. Their size (and position where applicable) will be fixed in this case. -.. note:: All capture and output devices must support the +.. note:: + + All capture and output devices must support the :ref:`VIDIOC_CROPCAP <VIDIOC_CROPCAP>` ioctl such that applications can determine if scaling takes place. @@ -144,7 +148,9 @@ reopening a device, such that piping data into or out of a device will work without special preparations. More advanced applications should ensure the parameters are suitable before starting I/O. -.. note:: On the next two examples, a video capture device is assumed; +.. note:: + + On the next two examples, a video capture device is assumed; change ``V4L2_BUF_TYPE_VIDEO_CAPTURE`` for other types of device. Example: Resetting the cropping parameters diff --git a/Documentation/media/uapi/v4l/dev-codec.rst b/Documentation/media/uapi/v4l/dev-codec.rst index dfb20328e34d..d9f218449ddd 100644 --- a/Documentation/media/uapi/v4l/dev-codec.rst +++ b/Documentation/media/uapi/v4l/dev-codec.rst @@ -21,7 +21,9 @@ for both capture and output to start the codec. Video compression codecs use the MPEG controls to setup their codec parameters -.. note:: The MPEG controls actually support many more codecs than +.. note:: + + The MPEG controls actually support many more codecs than just MPEG. See :ref:`mpeg-controls`. Memory-to-memory devices can often be used as a shared resource: you can diff --git a/Documentation/media/uapi/v4l/dev-osd.rst b/Documentation/media/uapi/v4l/dev-osd.rst index fadda131f020..4e1ee79ec334 100644 --- a/Documentation/media/uapi/v4l/dev-osd.rst +++ b/Documentation/media/uapi/v4l/dev-osd.rst @@ -16,7 +16,9 @@ this interface, which borrows structures and ioctls of the The OSD function is accessible through the same character special file as the :ref:`Video Output <capture>` function. -.. note:: The default function of such a ``/dev/video`` device is video +.. note:: + + The default function of such a ``/dev/video`` device is video capturing or output. The OSD function is only available after calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. diff --git a/Documentation/media/uapi/v4l/dev-overlay.rst b/Documentation/media/uapi/v4l/dev-overlay.rst index 92b4471b0c6e..d47a6bbc2e98 100644 --- a/Documentation/media/uapi/v4l/dev-overlay.rst +++ b/Documentation/media/uapi/v4l/dev-overlay.rst @@ -19,7 +19,9 @@ video into a window. Video overlay devices are accessed through the same character special files as :ref:`video capture <capture>` devices. -.. note:: The default function of a ``/dev/video`` device is video +.. note:: + + The default function of a ``/dev/video`` device is video capturing. The overlay function is only available after calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. @@ -236,7 +238,9 @@ exceeded are undefined. [#f3]_ :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>`, :ref:`framebuffer-flags`). - .. note:: This field was added in Linux 2.6.23, extending the + .. note:: + + This field was added in Linux 2.6.23, extending the structure. However the :ref:`VIDIOC_[G|S|TRY]_FMT <VIDIOC_G_FMT>` ioctls, which take a pointer to a :ref:`v4l2_format <v4l2-format>` parent structure with padding bytes at the end, are not affected. diff --git a/Documentation/media/uapi/v4l/dev-rds.rst b/Documentation/media/uapi/v4l/dev-rds.rst index cd6ad63cb90b..fa32538d4c1f 100644 --- a/Documentation/media/uapi/v4l/dev-rds.rst +++ b/Documentation/media/uapi/v4l/dev-rds.rst @@ -14,7 +14,9 @@ at devices capable of receiving and/or transmitting RDS information. For more information see the core RDS standard :ref:`iec62106` and the RBDS standard :ref:`nrsc4`. -.. note:: Note that the RBDS standard as is used in the USA is almost +.. note:: + + Note that the RBDS standard as is used in the USA is almost identical to the RDS standard. Any RDS decoder/encoder can also handle RBDS. Only some of the fields have slightly different meanings. See the RBDS standard for more information. diff --git a/Documentation/media/uapi/v4l/extended-controls.rst b/Documentation/media/uapi/v4l/extended-controls.rst index 71071d73747d..782f7f3c2209 100644 --- a/Documentation/media/uapi/v4l/extended-controls.rst +++ b/Documentation/media/uapi/v4l/extended-controls.rst @@ -184,7 +184,9 @@ Codec Control Reference Below all controls within the Codec control class are described. First the generic controls, then controls specific for certain hardware. -.. note:: These controls are applicable to all codecs and not just MPEG. The +.. note:: + + These controls are applicable to all codecs and not just MPEG. The defines are prefixed with V4L2_CID_MPEG/V4L2_MPEG as the controls were originally made for MPEG codecs and later extended to cover all encoding formats. diff --git a/Documentation/media/uapi/v4l/func-mmap.rst b/Documentation/media/uapi/v4l/func-mmap.rst index c156fb7b7422..639fef5b4f78 100644 --- a/Documentation/media/uapi/v4l/func-mmap.rst +++ b/Documentation/media/uapi/v4l/func-mmap.rst @@ -78,7 +78,9 @@ Arguments ``MAP_SHARED`` allows applications to share the mapped memory with other (e. g. child-) processes. - .. note:: The Linux ``videobuf`` module which is used by some + .. note:: + + The Linux ``videobuf`` module which is used by some drivers supports only ``MAP_SHARED``. ``MAP_PRIVATE`` requests copy-on-write semantics. V4L2 applications should not set the ``MAP_PRIVATE``, ``MAP_DENYWRITE``, ``MAP_EXECUTABLE`` or ``MAP_ANON`` diff --git a/Documentation/media/uapi/v4l/pixfmt-006.rst b/Documentation/media/uapi/v4l/pixfmt-006.rst index 987b9a8a9eb4..1c8321f9b1fb 100644 --- a/Documentation/media/uapi/v4l/pixfmt-006.rst +++ b/Documentation/media/uapi/v4l/pixfmt-006.rst @@ -19,7 +19,9 @@ colorspace field of struct :ref:`v4l2_pix_format <v4l2-pix-format>` or struct :ref:`v4l2_pix_format_mplane <v4l2-pix-format-mplane>` needs to be filled in. -.. note:: The default R'G'B' quantization is full range for all +.. note:: + + The default R'G'B' quantization is full range for all colorspaces except for BT.2020 which uses limited range R'G'B' quantization. diff --git a/Documentation/media/uapi/v4l/pixfmt-007.rst b/Documentation/media/uapi/v4l/pixfmt-007.rst index 8c946b0c63a0..39753f6f7b83 100644 --- a/Documentation/media/uapi/v4l/pixfmt-007.rst +++ b/Documentation/media/uapi/v4l/pixfmt-007.rst @@ -538,7 +538,9 @@ projectors that use the DCI-P3 colorspace. The default transfer function is ``V4L2_XFER_FUNC_DCI_P3``. The default Y'CbCr encoding is ``V4L2_YCBCR_ENC_709``. -.. note:: Note that this colorspace does not specify a +.. note:: + + Note that this colorspace does not specify a Y'CbCr encoding since it is not meant to be encoded to Y'CbCr. So this default Y'CbCr encoding was picked because it is the HDTV encoding. The default Y'CbCr quantization is limited range. The chromaticities of the @@ -754,7 +756,9 @@ reference are: - 0.316 -.. note:: This colorspace uses Illuminant C instead of D65 as the white +.. note:: + + This colorspace uses Illuminant C instead of D65 as the white reference. To correctly convert an image in this colorspace to another that uses D65 you need to apply a chromatic adaptation algorithm such as the Bradford method. @@ -888,7 +892,9 @@ reference are identical to sRGB. The transfer function use is with full range quantization where Y' is scaled to [0…255] and Cb/Cr are scaled to [-128…128] and then clipped to [-128…127]. -.. note:: The JPEG standard does not actually store colorspace +.. note:: + + The JPEG standard does not actually store colorspace information. So if something other than sRGB is used, then the driver will have to set that information explicitly. Effectively ``V4L2_COLORSPACE_JPEG`` can be considered to be an abbreviation for diff --git a/Documentation/media/uapi/v4l/pixfmt-sbggr16.rst b/Documentation/media/uapi/v4l/pixfmt-sbggr16.rst index 14446ed7f650..7f295b48748c 100644 --- a/Documentation/media/uapi/v4l/pixfmt-sbggr16.rst +++ b/Documentation/media/uapi/v4l/pixfmt-sbggr16.rst @@ -19,7 +19,9 @@ This format is similar to has a depth of 16 bits. The least significant byte is stored at lower memory addresses (little-endian). -..note:: The actual sampling precision may be lower than 16 bits, +..note:: + + The actual sampling precision may be lower than 16 bits, for example 10 bits per pixel with values in tange 0 to 1023. **Byte Order.** diff --git a/Documentation/media/uapi/v4l/pixfmt-y16-be.rst b/Documentation/media/uapi/v4l/pixfmt-y16-be.rst index 37fa099c16a6..b16874951f0f 100644 --- a/Documentation/media/uapi/v4l/pixfmt-y16-be.rst +++ b/Documentation/media/uapi/v4l/pixfmt-y16-be.rst @@ -17,7 +17,9 @@ Description This is a grey-scale image with a depth of 16 bits per pixel. The most significant byte is stored at lower memory addresses (big-endian). -.. note:: Tthe actual sampling precision may be lower than 16 bits, for +.. note:: + + The actual sampling precision may be lower than 16 bits, for example 10 bits per pixel with values in range 0 to 1023. **Byte Order.** diff --git a/Documentation/media/uapi/v4l/pixfmt-y16.rst b/Documentation/media/uapi/v4l/pixfmt-y16.rst index 4c41c042188b..10e2824da147 100644 --- a/Documentation/media/uapi/v4l/pixfmt-y16.rst +++ b/Documentation/media/uapi/v4l/pixfmt-y16.rst @@ -17,7 +17,9 @@ Description This is a grey-scale image with a depth of 16 bits per pixel. The least significant byte is stored at lower memory addresses (little-endian). -.. note:: The actual sampling precision may be lower than 16 bits, for +.. note:: + + The actual sampling precision may be lower than 16 bits, for example 10 bits per pixel with values in range 0 to 1023. **Byte Order.** diff --git a/Documentation/media/uapi/v4l/standard.rst b/Documentation/media/uapi/v4l/standard.rst index c4f678f545ec..5dd341f18839 100644 --- a/Documentation/media/uapi/v4l/standard.rst +++ b/Documentation/media/uapi/v4l/standard.rst @@ -41,7 +41,9 @@ output applications call the :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and *received* standard can be sensed with the :ref:`VIDIOC_QUERYSTD` ioctl. -..note:: The parameter of all these ioctls is a pointer to a +..note:: + + The parameter of all these ioctls is a pointer to a :ref:`v4l2_std_id <v4l2-std-id>` type (a standard set), *not* an index into the standard enumeration. Drivers must implement all video standard ioctls when the device has one or more video inputs or outputs. diff --git a/Documentation/media/uapi/v4l/tuner.rst b/Documentation/media/uapi/v4l/tuner.rst index 37eb4b9b95fb..c3df65c2e320 100644 --- a/Documentation/media/uapi/v4l/tuner.rst +++ b/Documentation/media/uapi/v4l/tuner.rst @@ -28,7 +28,9 @@ struct :ref:`v4l2_tuner <v4l2-tuner>` returned by :ref:`VIDIOC_G_TUNER <VIDIOC_G also contains signal status information applicable when the tuner of the current video or radio input is queried. -.. note:: :ref:`VIDIOC_S_TUNER <VIDIOC_G_TUNER>` does not switch the +.. note:: + + :ref:`VIDIOC_S_TUNER <VIDIOC_G_TUNER>` does not switch the current tuner, when there is more than one at all. The tuner is solely determined by the current video input. Drivers must support both ioctls and set the ``V4L2_CAP_TUNER`` flag in the struct :ref:`v4l2_capability diff --git a/Documentation/media/uapi/v4l/userp.rst b/Documentation/media/uapi/v4l/userp.rst index 1d8b14bd4cdc..0371e068c50b 100644 --- a/Documentation/media/uapi/v4l/userp.rst +++ b/Documentation/media/uapi/v4l/userp.rst @@ -88,7 +88,9 @@ To start and stop capturing or output applications call the :ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` and :ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` ioctl. -.. note:: ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` removes all buffers from +.. note:: + + ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` removes all buffers from both queues and unlocks all buffers as a side effect. Since there is no notion of doing anything "now" on a multitasking system, if an application needs to synchronize with another event it should examine diff --git a/Documentation/media/uapi/v4l/vidioc-dv-timings-cap.rst b/Documentation/media/uapi/v4l/vidioc-dv-timings-cap.rst index 6e05957013bb..c390412d5aa9 100644 --- a/Documentation/media/uapi/v4l/vidioc-dv-timings-cap.rst +++ b/Documentation/media/uapi/v4l/vidioc-dv-timings-cap.rst @@ -39,7 +39,9 @@ initialize the ``pad`` field to 0, zero the reserved array of struct ``VIDIOC_DV_TIMINGS_CAP`` ioctl on a video node and the driver will fill in the structure. -.. note:: Drivers may return different values after +.. note:: + + Drivers may return different values after switching the video input or output. When implemented by the driver DV capabilities of subdevices can be diff --git a/Documentation/media/uapi/v4l/vidioc-enum-dv-timings.rst b/Documentation/media/uapi/v4l/vidioc-enum-dv-timings.rst index 3ba75d3fb93c..764d6cea601c 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-dv-timings.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-dv-timings.rst @@ -49,7 +49,9 @@ error code when the index is out of bounds. To enumerate all supported DV timings, applications shall begin at index zero, incrementing by one until the driver returns ``EINVAL``. -.. note:: Drivers may enumerate a different set of DV timings after +.. note:: + + Drivers may enumerate a different set of DV timings after switching the video input or output. When implemented by the driver DV timings of subdevices can be queried diff --git a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst index 90996f69d6ae..4715261631ab 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst @@ -40,7 +40,9 @@ fill the rest of the structure or return an ``EINVAL`` error code. All formats are enumerable by beginning at index zero and incrementing by one until ``EINVAL`` is returned. -.. note:: After switching input or output the list of enumerated image +.. note:: + + After switching input or output the list of enumerated image formats may be different. @@ -51,7 +53,6 @@ one until ``EINVAL`` is returned. :stub-columns: 0 :widths: 1 1 2 - - .. row 1 - __u32 @@ -113,7 +114,9 @@ one until ``EINVAL`` is returned. Several image formats are already defined by this specification in :ref:`pixfmt`. - .. attention:: These codes are not the same as those used + .. attention:: + + These codes are not the same as those used in the Windows world. - .. row 7 diff --git a/Documentation/media/uapi/v4l/vidioc-enum-frameintervals.rst b/Documentation/media/uapi/v4l/vidioc-enum-frameintervals.rst index ceae6003039e..9c22a3a6938f 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-frameintervals.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-frameintervals.rst @@ -73,7 +73,9 @@ the device supports. Only for the ``V4L2_FRMIVAL_TYPE_DISCRETE`` type does it make sense to increase the index value to receive more frame intervals. -.. note:: The order in which the frame intervals are returned has no +.. note:: + + The order in which the frame intervals are returned has no special meaning. In particular does it not say anything about potential default frame intervals. diff --git a/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst b/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst index 8b268354d442..6e2adf6c23a3 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst @@ -72,7 +72,9 @@ the ``type`` field to determine the type of frame size enumeration the device supports. Only for the ``V4L2_FRMSIZE_TYPE_DISCRETE`` type does it make sense to increase the index value to receive more frame sizes. -.. note:: The order in which the frame sizes are returned has no special +.. note:: + + The order in which the frame sizes are returned has no special meaning. In particular does it not say anything about potential default format sizes. diff --git a/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst b/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst index 00ab5e19cc1d..ccf308bd9423 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst @@ -129,7 +129,9 @@ of the corresponding tuner/modulator is set. - :cspan:`2` The supported modulation systems of this frequency band. See :ref:`band-modulation`. - .. note:: Currently only one modulation system per frequency band + .. note:: + + Currently only one modulation system per frequency band is supported. More work will need to be done if multiple modulation systems are possible. Contact the linux-media mailing list diff --git a/Documentation/media/uapi/v4l/vidioc-enumaudioout.rst b/Documentation/media/uapi/v4l/vidioc-enumaudioout.rst index cde1db55834f..3112b43242f2 100644 --- a/Documentation/media/uapi/v4l/vidioc-enumaudioout.rst +++ b/Documentation/media/uapi/v4l/vidioc-enumaudioout.rst @@ -41,7 +41,9 @@ structure or return an ``EINVAL`` error code when the index is out of bounds. To enumerate all audio outputs applications shall begin at index zero, incrementing by one until the driver returns ``EINVAL``. -.. note:: Connectors on a TV card to loop back the received audio signal +.. note:: + + Connectors on a TV card to loop back the received audio signal to a sound card are not audio outputs in this sense. See :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDOUT>` for a description of struct diff --git a/Documentation/media/uapi/v4l/vidioc-g-audioout.rst b/Documentation/media/uapi/v4l/vidioc-g-audioout.rst index b1c1bfeb251e..c9e9a550e86d 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-audioout.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-audioout.rst @@ -51,7 +51,9 @@ return the ``EINVAL`` error code when the index is out of bounds. This is a write-only ioctl, it does not return the current audio output attributes as ``VIDIOC_G_AUDOUT`` does. -.. note:: Connectors on a TV card to loop back the received audio signal +.. note:: + + Connectors on a TV card to loop back the received audio signal to a sound card are not audio outputs in this sense. diff --git a/Documentation/media/uapi/v4l/vidioc-g-edid.rst b/Documentation/media/uapi/v4l/vidioc-g-edid.rst index 1a982b68a72f..b881098b8964 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-edid.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-edid.rst @@ -67,7 +67,9 @@ total number of available EDID blocks and it will return 0 without copying any data. This is an easy way to discover how many EDID blocks there are. -.. note:: If there are no EDID blocks available at all, then +.. note:: + + If there are no EDID blocks available at all, then the driver will set ``blocks`` to 0 and it returns 0. To set the EDID blocks of a receiver the application has to fill in the diff --git a/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst b/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst index 39e24ad4b825..c91039b16d49 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst @@ -127,7 +127,9 @@ still cause this situation. to a value large enough to store the payload result and ``ENOSPC`` is returned. - .. note:: For string controls, this ``size`` field should + .. note:: + + For string controls, this ``size`` field should not be confused with the length of the string. This field refers to the size of the memory that contains the string. The actual *length* of the string may well be much smaller. @@ -265,7 +267,9 @@ still cause this situation. control and ``V4L2_CTRL_WHICH_DEF_VAL`` will return the default value of the control. - .. note:: You can only get the default value of the control, + .. note:: + + You can only get the default value of the control, you cannot set or try it. For backwards compatibility you can also use a control class here diff --git a/Documentation/media/uapi/v4l/vidioc-g-modulator.rst b/Documentation/media/uapi/v4l/vidioc-g-modulator.rst index a2e8c73f0678..fcb2e4896d4d 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-modulator.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-modulator.rst @@ -130,7 +130,9 @@ To change the radio frequency the shall be modulated. It contains a set of flags as defined in :ref:`modulator-txsubchans`. - .. note:: The tuner ``rxsubchans`` flags are reused, but the + .. note:: + + The tuner ``rxsubchans`` flags are reused, but the semantics are different. Video output devices are assumed to have an analog or PCM audio input with 1-3 channels. The ``txsubchans`` flags select one or more channels diff --git a/Documentation/media/uapi/v4l/vidioc-g-sliced-vbi-cap.rst b/Documentation/media/uapi/v4l/vidioc-g-sliced-vbi-cap.rst index f1f661d0200c..f3db6f677650 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-sliced-vbi-cap.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-sliced-vbi-cap.rst @@ -40,7 +40,9 @@ output device, applications initialize the ``type`` field of a struct driver fills in the remaining fields or returns an ``EINVAL`` error code if the sliced VBI API is unsupported or ``type`` is invalid. -.. note:: The ``type`` field was added, and the ioctl changed from read-only +.. note:: + + The ``type`` field was added, and the ioctl changed from read-only to write-read, in Linux 2.6.19. diff --git a/Documentation/media/uapi/v4l/vidioc-g-tuner.rst b/Documentation/media/uapi/v4l/vidioc-g-tuner.rst index 614db06b8b4b..d209736d6a53 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-tuner.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-tuner.rst @@ -391,7 +391,9 @@ To change the radio frequency the carrier for a monaural secondary language. Only ``V4L2_TUNER_ANALOG_TV`` tuners can have this capability. - .. note:: The ``V4L2_TUNER_CAP_LANG2`` and ``V4L2_TUNER_CAP_SAP`` + .. note:: + + The ``V4L2_TUNER_CAP_LANG2`` and ``V4L2_TUNER_CAP_SAP`` flags are synonyms. ``V4L2_TUNER_CAP_SAP`` applies when the tuner supports the ``V4L2_STD_NTSC_M`` video standard. @@ -502,7 +504,9 @@ To change the radio frequency the - The tuner receives a Second Audio Program. - .. note:: The ``V4L2_TUNER_SUB_LANG2`` and ``V4L2_TUNER_SUB_SAP`` + .. note:: + + The ``V4L2_TUNER_SUB_LANG2`` and ``V4L2_TUNER_SUB_SAP`` flags are synonyms. The ``V4L2_TUNER_SUB_SAP`` flag applies when the current video standard is ``V4L2_STD_NTSC_M``. diff --git a/Documentation/media/uapi/v4l/vidioc-qbuf.rst b/Documentation/media/uapi/v4l/vidioc-qbuf.rst index 3b927f36fb5b..31c360d7d1a6 100644 --- a/Documentation/media/uapi/v4l/vidioc-qbuf.rst +++ b/Documentation/media/uapi/v4l/vidioc-qbuf.rst @@ -137,7 +137,9 @@ EIO ``VIDIOC_DQBUF`` failed due to an internal error. Can also indicate temporary problems like signal loss. - .. note:: The driver might dequeue an (empty) buffer despite returning + .. note:: + + The driver might dequeue an (empty) buffer despite returning an error, or even stop capturing. Reusing such buffer may be unsafe though and its details (e.g. ``index``) may not be returned either. It is recommended that drivers indicate recoverable errors by setting diff --git a/Documentation/media/uapi/v4l/vidioc-query-dv-timings.rst b/Documentation/media/uapi/v4l/vidioc-query-dv-timings.rst index 416d8d604af4..6a87f44cdf3f 100644 --- a/Documentation/media/uapi/v4l/vidioc-query-dv-timings.rst +++ b/Documentation/media/uapi/v4l/vidioc-query-dv-timings.rst @@ -39,7 +39,9 @@ similar to sensing the video standard. To do so, applications call :ref:`v4l2_dv_timings <v4l2-dv-timings>`. Once the hardware detects the timings, it will fill in the timings structure. -.. note:: Drivers shall *not* switch timings automatically if new +.. note:: + + Drivers shall *not* switch timings automatically if new timings are detected. Instead, drivers should send the ``V4L2_EVENT_SOURCE_CHANGE`` event (if they support this) and expect that userspace will take action by calling :ref:`VIDIOC_QUERY_DV_TIMINGS`. diff --git a/Documentation/media/uapi/v4l/vidioc-queryctrl.rst b/Documentation/media/uapi/v4l/vidioc-queryctrl.rst index 8d6e61a7284d..937ce9e32a79 100644 --- a/Documentation/media/uapi/v4l/vidioc-queryctrl.rst +++ b/Documentation/media/uapi/v4l/vidioc-queryctrl.rst @@ -84,7 +84,9 @@ fills the rest of the structure or returns an ``EINVAL`` error code when the :ref:`v4l2_queryctrl <v4l2-queryctrl>` ``minimum`` to ``maximum``, inclusive. -.. note:: It is possible for ``VIDIOC_QUERYMENU`` to return +.. note:: + + It is possible for ``VIDIOC_QUERYMENU`` to return an ``EINVAL`` error code for some indices between ``minimum`` and ``maximum``. In that case that particular menu item is not supported by this driver. Also note that the ``minimum`` value is not necessarily 0. @@ -188,7 +190,9 @@ See also the examples in :ref:`control`. ``_BITMASK``, ``_MENU`` or ``_INTEGER_MENU`` control. Not valid for other types of controls. - .. note:: Drivers reset controls to their default value only when + .. note:: + + Drivers reset controls to their default value only when the driver is first loaded, never afterwards. - .. row 8 @@ -306,7 +310,9 @@ See also the examples in :ref:`control`. ``_BOOLEAN``, ``_BITMASK``, ``_MENU``, ``_INTEGER_MENU``, ``_U8`` or ``_U16`` control. Not valid for other types of controls. - .. note:: Drivers reset controls to their default value only when + .. note:: + + Drivers reset controls to their default value only when the driver is first loaded, never afterwards. - .. row 8 @@ -728,7 +734,9 @@ See also the examples in :ref:`control`. case the hardware calculates the gain value based on the lighting conditions which can change over time. - .. note:: Setting a new value for a volatile control will have no + .. note:: + + Setting a new value for a volatile control will have no effect and no ``V4L2_EVENT_CTRL_CH_VALUE`` will be sent, unless the ``V4L2_CTRL_FLAG_EXECUTE_ON_WRITE`` flag (see below) is also set. Otherwise the new value will just be ignored. diff --git a/Documentation/media/uapi/v4l/vidioc-querystd.rst b/Documentation/media/uapi/v4l/vidioc-querystd.rst index b4a4e222c7b0..cb03d249417c 100644 --- a/Documentation/media/uapi/v4l/vidioc-querystd.rst +++ b/Documentation/media/uapi/v4l/vidioc-querystd.rst @@ -43,7 +43,9 @@ will return V4L2_STD_UNKNOWN. When detection is not possible or fails, the set must contain all standards supported by the current video input or output. -.. note:: Drivers shall *not* switch the video standard +.. note:: + + Drivers shall *not* switch the video standard automatically if a new video standard is detected. Instead, drivers should send the ``V4L2_EVENT_SOURCE_CHANGE`` event (if they support this) and expect that userspace will take action by calling diff --git a/Documentation/media/uapi/v4l/vidioc-streamon.rst b/Documentation/media/uapi/v4l/vidioc-streamon.rst index bb23745ebcaf..7fa4362f9a81 100644 --- a/Documentation/media/uapi/v4l/vidioc-streamon.rst +++ b/Documentation/media/uapi/v4l/vidioc-streamon.rst @@ -76,7 +76,9 @@ then 0 is returned. Nothing happens in the case of ``VIDIOC_STREAMON``, but ``VIDIOC_STREAMOFF`` will return queued buffers to their starting state as mentioned above. -.. note:: Applications can be preempted for unknown periods right before +.. note:: + + Applications can be preempted for unknown periods right before or after the ``VIDIOC_STREAMON`` or ``VIDIOC_STREAMOFF`` calls, there is no notion of starting or stopping "now". Buffer timestamps can be used to synchronize with other events. diff --git a/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst b/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst index 3f28e8c47960..86b16faa41bb 100644 --- a/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst +++ b/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst @@ -54,7 +54,9 @@ using the :ref:`VIDIOC_DQEVENT` ioctl. - Type of the event, see :ref:`event-type`. - .. note:: ``V4L2_EVENT_ALL`` can be used with + .. note:: + + ``V4L2_EVENT_ALL`` can be used with :ref:`VIDIOC_UNSUBSCRIBE_EVENT <VIDIOC_SUBSCRIBE_EVENT>` for unsubscribing all events at once. |