diff options
| author | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2016-07-10 11:57:43 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2016-07-10 12:06:28 -0300 |
| commit | 706f8a9975cb8889742d1f606ff466205ed29805 (patch) | |
| tree | 53f11f25ecbab359cfa29e56c0effff67e4c0500 /Documentation/media/uapi/v4l | |
| parent | fed7b888f69f70fc35c184677b2e8f59cb3945cb (diff) | |
[media] doc-rst: improve display of notes and warnings
There are several notes and warning mesages in the middle of
the media docbook. Use the ReST tags for that, as it makes
them visually better and hightlights them.
While here, modify a few ones to make them clearer.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Diffstat (limited to 'Documentation/media/uapi/v4l')
46 files changed, 327 insertions, 267 deletions
diff --git a/Documentation/media/uapi/v4l/audio.rst b/Documentation/media/uapi/v4l/audio.rst index 47f8334f071e..cd3057326de7 100644 --- a/Documentation/media/uapi/v4l/audio.rst +++ b/Documentation/media/uapi/v4l/audio.rst @@ -35,11 +35,12 @@ The struct :ref:`v4l2_audio <v4l2-audio>` returned by the 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 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. +audio input and output, respectively. + +.. 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. To select an audio input and change its properties applications call the :ref:`VIDIOC_S_AUDIO <VIDIOC_G_AUDIO>` ioctl. To select an audio diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst index b195eb5b63a1..16cdd8e2c4d7 100644 --- a/Documentation/media/uapi/v4l/buffer.rst +++ b/Documentation/media/uapi/v4l/buffer.rst @@ -166,11 +166,11 @@ 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 - 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`. + .. 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 @@ -297,8 +297,10 @@ struct v4l2_plane stream, applications when it refers to an output stream. If the application sets this to 0 for an output stream, then ``bytesused`` will be set to the size of the plane (see the - ``length`` field of this struct) by the driver. Note that the - actual image data starts at ``data_offset`` which may not be 0. + ``length`` field of this struct) by the driver. + + .. note:: Note that the actual image data starts at ``data_offset`` + which may not be 0. - .. row 2 @@ -367,10 +369,11 @@ struct v4l2_plane - - Offset in bytes to video data in the plane. Drivers must set this 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 size of the image in the plane is - ``bytesused``-``data_offset`` at offset ``data_offset`` from the - start of the plane. + it refers to an output stream. + + .. 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. - .. row 8 diff --git a/Documentation/media/uapi/v4l/crop.rst b/Documentation/media/uapi/v4l/crop.rst index 51b19491c302..0913822347af 100644 --- a/Documentation/media/uapi/v4l/crop.rst +++ b/Documentation/media/uapi/v4l/crop.rst @@ -15,9 +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>`, -:ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and :ref:`VIDIOC_S_CROP -<VIDIOC_G_CROP>` ioctls apply to input as well as output devices. +.. 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. Scaling requires a source and a target. On a video capture or overlay device the source is the video signal, and the cropping ioctls determine @@ -38,9 +38,9 @@ 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 -:ref:`VIDIOC_CROPCAP <VIDIOC_CROPCAP>` ioctl such that applications can -determine if scaling takes place. +.. note:: All capture and output devices must support the + :ref:`VIDIOC_CROPCAP <VIDIOC_CROPCAP>` ioctl such that applications + can determine if scaling takes place. Cropping Structures @@ -144,8 +144,8 @@ 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; -change ``V4L2_BUF_TYPE_VIDEO_CAPTURE`` for other types of device. +.. 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 ========================================== @@ -207,7 +207,7 @@ Example: Simple downscaling Example: Selecting an output area ================================= -**NOTE:** This example assumes an output device. +.. note:: This example assumes an output device. .. code-block:: c @@ -246,7 +246,7 @@ Example: Selecting an output area Example: Current scaling factor and pixel aspect ================================================ -**NOTE:** This example assumes a video capture device. +.. note:: This example assumes a video capture device. .. code-block:: c diff --git a/Documentation/media/uapi/v4l/dev-capture.rst b/Documentation/media/uapi/v4l/dev-capture.rst index 16030a8354fd..8d049471e1c2 100644 --- a/Documentation/media/uapi/v4l/dev-capture.rst +++ b/Documentation/media/uapi/v4l/dev-capture.rst @@ -15,7 +15,9 @@ Conventionally V4L2 video capture devices are accessed through character device special files named ``/dev/video`` and ``/dev/video0`` to ``/dev/video63`` with major number 81 and minor numbers 0 to 63. ``/dev/video`` is typically a symbolic link to the preferred video -device. Note the same device files are used for video output devices. +device. + +.. note:: The same device file names are used for video output devices. Querying Capabilities diff --git a/Documentation/media/uapi/v4l/dev-codec.rst b/Documentation/media/uapi/v4l/dev-codec.rst index 7fd28d085c2c..dfb20328e34d 100644 --- a/Documentation/media/uapi/v4l/dev-codec.rst +++ b/Documentation/media/uapi/v4l/dev-codec.rst @@ -19,8 +19,10 @@ both sides and finally call :ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` for both capture and output to start the codec. Video compression codecs use the MPEG controls to setup their codec -parameters (note that the MPEG controls actually support many more -codecs than just MPEG). See :ref:`mpeg-controls`. +parameters + +.. 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 open the video node multiple times, each application setting up their diff --git a/Documentation/media/uapi/v4l/dev-effect.rst b/Documentation/media/uapi/v4l/dev-effect.rst index be4de3b0a025..b946cc9e1064 100644 --- a/Documentation/media/uapi/v4l/dev-effect.rst +++ b/Documentation/media/uapi/v4l/dev-effect.rst @@ -6,11 +6,10 @@ Effect Devices Interface ************************ - **Note** - - This interface has been be suspended from the V4L2 API implemented - in Linux 2.6 until we have more experience with effect device - interfaces. +.. note:: + This interface has been be suspended from the V4L2 API. + The implementation for such effects should be done + via mem2mem devices. A V4L2 video effect device can do image effects, filtering, or combine two or more images or image streams. For example video transitions or diff --git a/Documentation/media/uapi/v4l/dev-osd.rst b/Documentation/media/uapi/v4l/dev-osd.rst index 98570cea63a5..fadda131f020 100644 --- a/Documentation/media/uapi/v4l/dev-osd.rst +++ b/Documentation/media/uapi/v4l/dev-osd.rst @@ -14,10 +14,11 @@ this interface, which borrows structures and ioctls of the :ref:`Video Overlay <overlay>` interface. 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 capturing or output. -The OSD function is only available after calling the -:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. +as the :ref:`Video Output <capture>` function. + +.. 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. Querying Capabilities diff --git a/Documentation/media/uapi/v4l/dev-output.rst b/Documentation/media/uapi/v4l/dev-output.rst index 5063be7d4938..4f1123a0b40d 100644 --- a/Documentation/media/uapi/v4l/dev-output.rst +++ b/Documentation/media/uapi/v4l/dev-output.rst @@ -14,7 +14,9 @@ Conventionally V4L2 video output devices are accessed through character device special files named ``/dev/video`` and ``/dev/video0`` to ``/dev/video63`` with major number 81 and minor numbers 0 to 63. ``/dev/video`` is typically a symbolic link to the preferred video -device. Note the same device files are used for video capture devices. +device. + +..note:: The same device file names are used also for video capture devices. Querying Capabilities diff --git a/Documentation/media/uapi/v4l/dev-overlay.rst b/Documentation/media/uapi/v4l/dev-overlay.rst index bed00bf34982..bf8a418e7554 100644 --- a/Documentation/media/uapi/v4l/dev-overlay.rst +++ b/Documentation/media/uapi/v4l/dev-overlay.rst @@ -17,10 +17,11 @@ plants needed cooling towers this used to be the only way to put live 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 capturing. The overlay -function is only available after calling the -:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. +files as :ref:`video capture <capture>` devices. + +.. 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. The driver may support simultaneous overlay and capturing using the read/write and streaming I/O methods. If so, operation at the nominal @@ -235,10 +236,10 @@ exceeded are undefined. [3]_ :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>`, :ref:`framebuffer-flags`). - **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. + .. 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. .. _v4l2-clip: diff --git a/Documentation/media/uapi/v4l/dev-rds.rst b/Documentation/media/uapi/v4l/dev-rds.rst index 6a0b1a874668..cd6ad63cb90b 100644 --- a/Documentation/media/uapi/v4l/dev-rds.rst +++ b/Documentation/media/uapi/v4l/dev-rds.rst @@ -14,10 +14,10 @@ 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 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. +.. 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. The RBDS standard also specifies support for MMBS (Modified Mobile Search). This is a proprietary format which seems to be discontinued. diff --git a/Documentation/media/uapi/v4l/dev-subdev.rst b/Documentation/media/uapi/v4l/dev-subdev.rst index 39d3d860dda4..5a112eb7a245 100644 --- a/Documentation/media/uapi/v4l/dev-subdev.rst +++ b/Documentation/media/uapi/v4l/dev-subdev.rst @@ -72,14 +72,14 @@ reported on one (or several) V4L2 device nodes. Pad-level Formats ================= - **Warning** +.. warning:: - Pad-level formats are only applicable to very complex device that + Pad-level formats are only applicable to very complex devices that need to expose low-level format configuration to user space. Generic V4L2 applications do *not* need to use the API described in this section. - **Note** +.. note:: For the purpose of this section, the term *format* means the combination of media bus data format, frame width and frame height. diff --git a/Documentation/media/uapi/v4l/dmabuf.rst b/Documentation/media/uapi/v4l/dmabuf.rst index 57917fb98c7a..675768f7c66a 100644 --- a/Documentation/media/uapi/v4l/dmabuf.rst +++ b/Documentation/media/uapi/v4l/dmabuf.rst @@ -143,13 +143,16 @@ functions are always available. To start and stop capturing or displaying applications call the :ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` and -:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` ioctls. Note that -: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 -the struct :ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured or -outputted buffers. +:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` ioctls. + +.. 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 + the struct :ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured or + outputted buffers. Drivers implementing DMABUF importing I/O must support the :ref:`VIDIOC_REQBUFS <VIDIOC_REQBUFS>`, :ref:`VIDIOC_QBUF <VIDIOC_QBUF>`, diff --git a/Documentation/media/uapi/v4l/extended-controls.rst b/Documentation/media/uapi/v4l/extended-controls.rst index 26eb6ee851c3..11d15d3190e9 100644 --- a/Documentation/media/uapi/v4l/extended-controls.rst +++ b/Documentation/media/uapi/v4l/extended-controls.rst @@ -84,17 +84,20 @@ themselves than is possible with particular, this ioctl gives the dimensions of the N-dimensional array if this control consists of more than one element. -It is important to realize that due to the flexibility of controls it is -necessary to check whether the control you want to set actually is -supported in the driver and what the valid range of values is. So use -the :ref:`VIDIOC_QUERYCTRL` (or -:ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>`) and -:ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>` ioctls to check this. Also -note that it is possible that some of the menu indices in a control of -type ``V4L2_CTRL_TYPE_MENU`` may not be supported (``VIDIOC_QUERYMENU`` -will return an error). A good example is the list of supported MPEG -audio bitrates. Some drivers only support one or two bitrates, others -support a wider range. +.. note:: + + #. It is important to realize that due to the flexibility of controls it is + necessary to check whether the control you want to set actually is + supported in the driver and what the valid range of values is. So use + the :ref:`VIDIOC_QUERYCTRL` (or :ref:`VIDIOC_QUERY_EXT_CTRL + <VIDIOC_QUERYCTRL>`) and :ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>` + ioctls to check this. + + #. It is possible that some of the menu indices in a control of + type ``V4L2_CTRL_TYPE_MENU`` may not be supported (``VIDIOC_QUERYMENU`` + will return an error). A good example is the list of supported MPEG + audio bitrates. Some drivers only support one or two bitrates, others + support a wider range. All controls use machine endianness. @@ -181,10 +184,10 @@ 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 -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. +.. 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. Generic Codec Controls @@ -2282,13 +2285,15 @@ MFC 5.1 Control IDs ``V4L2_CID_MPEG_MFC51_VIDEO_RC_REACTION_COEFF (integer)`` Reaction coefficient for MFC rate control. Applicable to encoders. - Note 1: Valid only when the frame level RC is enabled. + .. note:: - Note 2: For tight CBR, this field must be small (ex. 2 ~ 10). For - VBR, this field must be large (ex. 100 ~ 1000). + #. Valid only when the frame level RC is enabled. - Note 3: It is not recommended to use the greater number than - FRAME_RATE * (10^9 / BIT_RATE). + #. For tight CBR, this field must be small (ex. 2 ~ 10). For + VBR, this field must be large (ex. 100 ~ 1000). + + #. It is not recommended to use the greater number than + FRAME_RATE * (10^9 / BIT_RATE). ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_DARK (boolean)`` Adaptive rate control for dark region. Valid only when H.264 and @@ -4107,14 +4112,16 @@ transmitters for `VGA <http://en.wikipedia.org/wiki/Vga>`__, the receiver or transmitter subdevice that implements them, so they are only exposed on the ``/dev/v4l-subdev*`` device node. -Note that these devices can have multiple input or output pads which are -hooked up to e.g. HDMI connectors. Even though the subdevice will -receive or transmit video from/to only one of those pads, the other pads -can still be active when it comes to EDID (Extended Display -Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital -Content Protection System, :ref:`hdcp`) processing, allowing the -device to do the fairly slow EDID/HDCP handling in advance. This allows -for quick switching between connectors. +.. note:: + + Note that these devices can have multiple input or output pads which are + hooked up to e.g. HDMI connectors. Even though the subdevice will + receive or transmit video from/to only one of those pads, the other pads + can still be active when it comes to EDID (Extended Display + Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital + Content Protection System, :ref:`hdcp`) processing, allowing the + device to do the fairly slow EDID/HDCP handling in advance. This allows + for quick switching between connectors. These pads appear in several of the controls in this section as bitmasks, one bit for each pad. Bit 0 corresponds to pad 0, bit 1 to pad diff --git a/Documentation/media/uapi/v4l/func-mmap.rst b/Documentation/media/uapi/v4l/func-mmap.rst index 3502c2afd894..c156fb7b7422 100644 --- a/Documentation/media/uapi/v4l/func-mmap.rst +++ b/Documentation/media/uapi/v4l/func-mmap.rst @@ -47,17 +47,20 @@ Arguments Regardless of the device type and the direction of data exchange it should be set to ``PROT_READ`` | ``PROT_WRITE``, permitting read and write access to image buffers. Drivers should support at least - this combination of flags. Note the Linux ``video-buf`` kernel - module, which is used by the bttv, saa7134, saa7146, cx88 and vivi - driver supports only ``PROT_READ`` | ``PROT_WRITE``. When the - driver does not support the desired protection the - :ref:`mmap() <func-mmap>` function fails. - - Note device memory accesses (e. g. the memory on a graphics card - with video capturing hardware) may incur a performance penalty - compared to main memory accesses, or reads may be significantly - slower than writes or vice versa. Other I/O methods may be more - efficient in this case. + this combination of flags. + + .. note:: + + #. The Linux ``videobuf`` kernel module, which is used by some + drivers supports only ``PROT_READ`` | ``PROT_WRITE``. When the + driver does not support the desired protection, the + :ref:`mmap() <func-mmap>` function fails. + + #. Device memory accesses (e. g. the memory on a graphics card + with video capturing hardware) may incur a performance penalty + compared to main memory accesses, or reads may be significantly + slower than writes or vice versa. Other I/O methods may be more + efficient in such case. ``flags`` The ``flags`` parameter specifies the type of the mapped object, @@ -73,11 +76,13 @@ Arguments One of the ``MAP_SHARED`` or ``MAP_PRIVATE`` flags must be set. ``MAP_SHARED`` allows applications to share the mapped memory with - other (e. g. child-) processes. Note the Linux ``video-buf`` module - which is used by the bttv, saa7134, saa7146, cx88 and vivi driver - 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`` flag. + other (e. g. child-) processes. + + .. 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`` + flags. ``fd`` File descriptor returned by :ref:`open() <func-open>`. diff --git a/Documentation/media/uapi/v4l/mmap.rst b/Documentation/media/uapi/v4l/mmap.rst index b01f4486499a..260c2db8916b 100644 --- a/Documentation/media/uapi/v4l/mmap.rst +++ b/Documentation/media/uapi/v4l/mmap.rst @@ -245,12 +245,14 @@ available. The :ref:`select() <func-select>` or :ref:`poll() 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 both queues 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 -the struct ::ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured -or outputted buffers. +<VIDIOC_STREAMON>` ioctl. + +.. note:::ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` + removes all buffers from both queues 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 + the struct ::ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured + or outputted buffers. Drivers implementing memory mapping I/O must support the :ref:`VIDIOC_REQBUFS <VIDIOC_REQBUFS>`, :ref:`VIDIOC_QUERYBUF diff --git a/Documentation/media/uapi/v4l/pixfmt-006.rst b/Documentation/media/uapi/v4l/pixfmt-006.rst index b9e7c6844020..9a0f494e2851 100644 --- a/Documentation/media/uapi/v4l/pixfmt-006.rst +++ b/Documentation/media/uapi/v4l/pixfmt-006.rst @@ -17,9 +17,11 @@ identifier (enum :ref:`v4l2_quantization <v4l2-quantization>`) to specify non-standard quantization methods. Most of the time only the 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 that the default R'G'B' quantization is full -range for all colorspaces except for BT.2020 which uses limited range -R'G'B' quantization. +needs to be filled in. + +.. 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. .. _v4l2-colorspace: diff --git a/Documentation/media/uapi/v4l/pixfmt-007.rst b/Documentation/media/uapi/v4l/pixfmt-007.rst index 5e39cda6147a..8c946b0c63a0 100644 --- a/Documentation/media/uapi/v4l/pixfmt-007.rst +++ b/Documentation/media/uapi/v4l/pixfmt-007.rst @@ -536,11 +536,13 @@ Colorspace DCI-P3 (V4L2_COLORSPACE_DCI_P3) The :ref:`smpte431` standard defines the colorspace used by cinema 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 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 -primary colors and the white reference are: +``V4L2_YCBCR_ENC_709``. + +.. 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 + primary colors and the white reference are: @@ -752,10 +754,10 @@ reference are: - 0.316 -Note that 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. +.. 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. The transfer function was never properly defined for NTSC 1953. The Rec. 709 transfer function is recommended in the literature: @@ -886,9 +888,9 @@ 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 that 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 -``V4L2_COLORSPACE_SRGB``, ``V4L2_YCBCR_ENC_601`` and -``V4L2_QUANTIZATION_FULL_RANGE``. +.. 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 + ``V4L2_COLORSPACE_SRGB``, ``V4L2_YCBCR_ENC_601`` and + ``V4L2_QUANTIZATION_FULL_RANGE``. diff --git a/Documentation/media/uapi/v4l/pixfmt-sbggr16.rst b/Documentation/media/uapi/v4l/pixfmt-sbggr16.rst index 2cfcc97b3c96..14446ed7f650 100644 --- a/Documentation/media/uapi/v4l/pixfmt-sbggr16.rst +++ b/Documentation/media/uapi/v4l/pixfmt-sbggr16.rst @@ -17,9 +17,10 @@ Description This format is similar to :ref:`V4L2_PIX_FMT_SBGGR8 <V4L2-PIX-FMT-SBGGR8>`, except each pixel 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, for example 10 bits per pixel with values in -range 0 to 1023. +memory addresses (little-endian). + +..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.** Each cell is one byte. diff --git a/Documentation/media/uapi/v4l/pixfmt-y16-be.rst b/Documentation/media/uapi/v4l/pixfmt-y16-be.rst index 0c61a10018c2..37fa099c16a6 100644 --- a/Documentation/media/uapi/v4l/pixfmt-y16-be.rst +++ b/Documentation/media/uapi/v4l/pixfmt-y16-be.rst @@ -15,9 +15,10 @@ 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 -the actual sampling precision may be lower than 16 bits, for example 10 -bits per pixel with values in range 0 to 1023. +significant byte is stored at lower memory addresses (big-endian). + +.. note:: Tthe actual sampling precision may be lower than 16 bits, for + example 10 bits per pixel with values in range 0 to 1023. **Byte Order.** Each cell is one byte. diff --git a/Documentation/media/uapi/v4l/pixfmt-y16.rst b/Documentation/media/uapi/v4l/pixfmt-y16.rst index a8d4b7192ae3..4c41c042188b 100644 --- a/Documentation/media/uapi/v4l/pixfmt-y16.rst +++ b/Documentation/media/uapi/v4l/pixfmt-y16.rst @@ -16,8 +16,9 @@ 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 -example 10 bits per pixel with values in range 0 to 1023. + +.. 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.** Each cell is one byte. diff --git a/Documentation/media/uapi/v4l/standard.rst b/Documentation/media/uapi/v4l/standard.rst index 529891cf3af2..9c390c2a128a 100644 --- a/Documentation/media/uapi/v4l/standard.rst +++ b/Documentation/media/uapi/v4l/standard.rst @@ -39,11 +39,12 @@ To query and select the standard used by the current video input or output applications call the :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctl, respectively. The *received* standard can be sensed with the -:ref:`VIDIOC_QUERYSTD` ioctl. Note that 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. +:ref:`VIDIOC_QUERYSTD` ioctl. + +..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. Special rules apply to devices such as USB cameras where the notion of video standards makes little sense. More generally for any capture or diff --git a/Documentation/media/uapi/v4l/tuner.rst b/Documentation/media/uapi/v4l/tuner.rst index 23d0e00aefdd..37eb4b9b95fb 100644 --- a/Documentation/media/uapi/v4l/tuner.rst +++ b/Documentation/media/uapi/v4l/tuner.rst @@ -26,13 +26,14 @@ To query and change tuner properties applications use the :ref:`VIDIOC_S_TUNER <VIDIOC_G_TUNER>` ioctls, respectively. The struct :ref:`v4l2_tuner <v4l2-tuner>` returned by :ref:`VIDIOC_G_TUNER <VIDIOC_G_TUNER>` also contains signal status information applicable when the tuner of the -current video or radio input is queried. Note that :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 <v4l2-capability>` returned by the -:ref:`VIDIOC_QUERYCAP` ioctl when the device has -one or more tuners. +current video or radio input is queried. + +.. 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 + <v4l2-capability>` returned by the :ref:`VIDIOC_QUERYCAP` ioctl when the + device has one or more tuners. Modulators diff --git a/Documentation/media/uapi/v4l/userp.rst b/Documentation/media/uapi/v4l/userp.rst index 0871c204dc6c..601963a33acb 100644 --- a/Documentation/media/uapi/v4l/userp.rst +++ b/Documentation/media/uapi/v4l/userp.rst @@ -86,13 +86,14 @@ available. 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 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 -the struct :ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured or -outputted buffers. +:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` ioctl. + +.. 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 + the struct :ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured or + outputted buffers. Drivers implementing user pointer I/O must support the :ref:`VIDIOC_REQBUFS <VIDIOC_REQBUFS>`, :ref:`VIDIOC_QBUF <VIDIOC_QBUF>`, diff --git a/Documentation/media/uapi/v4l/vidioc-dbg-g-chip-info.rst b/Documentation/media/uapi/v4l/vidioc-dbg-g-chip-info.rst index efa911c0fb19..f7e1b80af29e 100644 --- a/Documentation/media/uapi/v4l/vidioc-dbg-g-chip-info.rst +++ b/Documentation/media/uapi/v4l/vidioc-dbg-g-chip-info.rst @@ -33,7 +33,7 @@ Arguments Description =========== - **Note** +.. note:: This is an :ref:`experimental` interface and may change in the future. diff --git a/Documentation/media/uapi/v4l/vidioc-dbg-g-register.rst b/Documentation/media/uapi/v4l/vidioc-dbg-g-register.rst index 345aa321f380..09d2880e6170 100644 --- a/Documentation/media/uapi/v4l/vidioc-dbg-g-register.rst +++ b/Documentation/media/uapi/v4l/vidioc-dbg-g-register.rst @@ -35,7 +35,7 @@ Arguments Description =========== - **Note** +.. note:: This is an :ref:`experimental` interface and may change in the future. diff --git a/Documentation/media/uapi/v4l/vidioc-dv-timings-cap.rst b/Documentation/media/uapi/v4l/vidioc-dv-timings-cap.rst index 5a35bb254b4b..6e05957013bb 100644 --- a/Documentation/media/uapi/v4l/vidioc-dv-timings-cap.rst +++ b/Documentation/media/uapi/v4l/vidioc-dv-timings-cap.rst @@ -37,8 +37,10 @@ To query the capabilities of the DV receiver/transmitter applications initialize the ``pad`` field to 0, zero the reserved array of struct :ref:`v4l2_dv_timings_cap <v4l2-dv-timings-cap>` and call the ``VIDIOC_DV_TIMINGS_CAP`` ioctl on a video node and the driver will fill -in the structure. Note that drivers may return different values after -switching the video input or output. +in the structure. + +.. note:: Drivers may return different values after + switching the video input or output. When implemented by the driver DV capabilities of subdevices can be queried by calling the ``VIDIOC_SUBDEV_DV_TIMINGS_CAP`` ioctl directly diff --git a/Documentation/media/uapi/v4l/vidioc-enum-dv-timings.rst b/Documentation/media/uapi/v4l/vidioc-enum-dv-timings.rst index f0dd0c4ca7d0..3ba75d3fb93c 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-dv-timings.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-dv-timings.rst @@ -47,8 +47,10 @@ field, set the ``pad`` field to 0, zero the reserved array of struct structure. Drivers fill the rest of the structure or return an ``EINVAL`` 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 that drivers may enumerate a -different set of DV timings after switching the video input or output. +until the driver returns ``EINVAL``. + +.. 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 by calling the ``VIDIOC_SUBDEV_ENUM_DV_TIMINGS`` ioctl directly on a diff --git a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst index 257c624e27be..90996f69d6ae 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst @@ -40,8 +40,8 @@ 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 that after switching input or output the list of enumerated image -formats may be different. +.. note:: After switching input or output the list of enumerated image + formats may be different. .. _v4l2-fmtdesc: @@ -111,8 +111,10 @@ formats may be different. #define v4l2_fourcc(a,b,c,d) (((__u32)(a)<<0)|((__u32)(b)<<8)|((__u32)(c)<<16)|((__u32)(d)<<24)) Several image formats are already defined by this specification in - :ref:`pixfmt`. Note these codes are not the same as those used - in the Windows world. + :ref:`pixfmt`. + + .. 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 5d5de535a0fe..ceae6003039e 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-frameintervals.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-frameintervals.rst @@ -73,25 +73,21 @@ 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 that 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. +.. 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. Applications can assume that the enumeration data does not change without any interaction from the application itself. This means that the enumeration data is consistent if the application does not perform any other ioctl calls while it runs the frame interval enumeration. +.. note:: -Notes -===== - -- **Frame intervals and frame rates:** The V4L2 API uses frame + **Frame intervals and frame rates:** The V4L2 API uses frame intervals instead of frame rates. Given the frame interval the frame rate can be computed as follows: - - :: frame_rate = 1 / frame_interval diff --git a/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst b/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst index d3b2e97df6c9..8b268354d442 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-framesizes.rst @@ -72,9 +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 that 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. +.. 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. Applications can assume that the enumeration data does not change without any interaction from the application itself. This means that the diff --git a/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst b/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst index ea754f4f5532..00ab5e19cc1d 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst @@ -127,12 +127,14 @@ of the corresponding tuner/modulator is set. - ``modulation`` - :cspan:`2` The supported modulation systems of this frequency - band. See :ref:`band-modulation`. Note that 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 - (`https://linuxtv.org/lists.php <https://linuxtv.org/lists.php>`__) - if you need that functionality. + band. See :ref:`band-modulation`. + + .. 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 + (`https://linuxtv.org/lists.php <https://linuxtv.org/lists.php>`__) + if you need such functionality. - .. row 8 diff --git a/Documentation/media/uapi/v4l/vidioc-enumaudioout.rst b/Documentation/media/uapi/v4l/vidioc-enumaudioout.rst index 15bc5a40f4a6..cde1db55834f 100644 --- a/Documentation/media/uapi/v4l/vidioc-enumaudioout.rst +++ b/Documentation/media/uapi/v4l/vidioc-enumaudioout.rst @@ -41,8 +41,8 @@ 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 to a -sound card are not audio outputs in this sense. +.. 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 :ref:`v4l2_audioout <v4l2-audioout>`. diff --git a/Documentation/media/uapi/v4l/vidioc-enuminput.rst b/Documentation/media/uapi/v4l/vidioc-enuminput.rst index c1fc2e1f1d98..5060f54e3d18 100644 --- a/Documentation/media/uapi/v4l/vidioc-enuminput.rst +++ b/Documentation/media/uapi/v4l/vidioc-enuminput.rst @@ -233,8 +233,8 @@ at index zero, incrementing by one until the driver returns ``EINVAL``. - The input is connected to a device that produces a signal that is flipped vertically and does not correct this before passing the - signal to userspace. Note that a 180 degree rotation is the same - as HFLIP | VFLIP + signal to userspace. + .. note:: A 180 degree rotation is the same as HFLIP | VFLIP - .. row 8 diff --git a/Documentation/media/uapi/v4l/vidioc-g-audioout.rst b/Documentation/media/uapi/v4l/vidioc-g-audioout.rst index bee5f78ed7c1..b1c1bfeb251e 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-audioout.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-audioout.rst @@ -51,8 +51,8 @@ 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 to a -sound card are not audio outputs in this sense. +.. note:: Connectors on a TV card to loop back the received audio signal + to a sound card are not audio outputs in this sense. .. _v4l2-audioout: diff --git a/Documentation/media/uapi/v4l/vidioc-g-edid.rst b/Documentation/media/uapi/v4l/vidioc-g-edid.rst index 907b2c1764a3..1a982b68a72f 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-edid.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-edid.rst @@ -65,8 +65,10 @@ If ``start_block`` and ``blocks`` are both set to 0 when :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>` is called, then the driver will set ``blocks`` to the 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 that if there are no EDID blocks available at all, then -the driver will set ``blocks`` to 0 and it returns 0. +there are. + +.. 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 ``pad``, ``blocks`` and ``edid`` fields, set ``start_block`` to 0 and diff --git a/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst b/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst index 96b6eaca755c..39e24ad4b825 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst @@ -125,10 +125,12 @@ still cause this situation. the payload. If :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` finds that this value is less than is required to store the payload result, then it is set to a value large enough to store the payload result and ``ENOSPC`` is - returned. Note that 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. + returned. + + .. 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. - .. row 3 @@ -261,8 +263,10 @@ still cause this situation. - Which value of the control to get/set/try. ``V4L2_CTRL_WHICH_CUR_VAL`` will return the current value of the control and ``V4L2_CTRL_WHICH_DEF_VAL`` will return the default - value of the control. Please note that you can only get the - default value of the control, you cannot set or try it. + 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 (see :ref:`ctrl-class`). In that case all controls have to diff --git a/Documentation/media/uapi/v4l/vidioc-g-modulator.rst b/Documentation/media/uapi/v4l/vidioc-g-modulator.rst index 05d83610bdc5..a2e8c73f0678 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-modulator.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-modulator.rst @@ -128,12 +128,14 @@ To change the radio frequency the - With this field applications can determine how audio sub-carriers shall be modulated. It contains a set of flags as defined in - :ref:`modulator-txsubchans`. 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 for - modulation, together with some audio subprogram indicator, for - example a stereo pilot tone. + :ref:`modulator-txsubchans`. + + .. 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 + for modulation, together with some audio subprogram indicator, + for example, a stereo pilot tone. - .. row 7 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 76dd4ba3254f..f1f661d0200c 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-sliced-vbi-cap.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-sliced-vbi-cap.rst @@ -40,8 +40,8 @@ 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 -to write-read, in Linux 2.6.19. +.. note:: The ``type`` field was added, and the ioctl changed from read-only + to write-read, in Linux 2.6.19. .. _v4l2-sliced-vbi-cap: diff --git a/Documentation/media/uapi/v4l/vidioc-g-tuner.rst b/Documentation/media/uapi/v4l/vidioc-g-tuner.rst index a8d7ebd73e8a..c82085513bee 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-tuner.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-tuner.rst @@ -391,9 +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`` flags - are synonyms. ``V4L2_TUNER_CAP_SAP`` applies when the tuner - supports the ``V4L2_STD_NTSC_M`` video standard. + .. 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. - .. row 9 @@ -500,10 +500,11 @@ To change the radio frequency the - 0x0004 - - The tuner receives a Second Audio Program. 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``. + - The tuner receives a Second Audio Program. + + .. 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``. - .. row 6 @@ -578,9 +579,10 @@ To change the radio frequency the - Play the Second Audio Program. When the tuner receives no bilingual audio or SAP, or their reception is not supported the driver shall fall back to mono or stereo mode. Only - ``V4L2_TUNER_ANALOG_TV`` tuners support this mode. Note the - ``V4L2_TUNER_MODE_LANG2`` and ``V4L2_TUNER_MODE_SAP`` are - synonyms. + ``V4L2_TUNER_ANALOG_TV`` tuners support this mode. + + .. note:: The ``V4L2_TUNER_MODE_LANG2`` and ``V4L2_TUNER_MODE_SAP`` + are synonyms. - .. row 6 diff --git a/Documentation/media/uapi/v4l/vidioc-qbuf.rst b/Documentation/media/uapi/v4l/vidioc-qbuf.rst index 9870d243131a..3b927f36fb5b 100644 --- a/Documentation/media/uapi/v4l/vidioc-qbuf.rst +++ b/Documentation/media/uapi/v4l/vidioc-qbuf.rst @@ -135,14 +135,15 @@ EINVAL 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 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 the - ``V4L2_BUF_FLAG_ERROR`` and returning 0 instead. In that case the - application should be able to safely reuse the buffer and continue - streaming. + temporary problems like signal loss. + + .. 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 + the ``V4L2_BUF_FLAG_ERROR`` and returning 0 instead. In that case the + application should be able to safely reuse the buffer and continue + streaming. EPIPE ``VIDIOC_DQBUF`` returns this on an empty capture queue for mem2mem diff --git a/Documentation/media/uapi/v4l/vidioc-query-dv-timings.rst b/Documentation/media/uapi/v4l/vidioc-query-dv-timings.rst index 338b80df5b9b..416d8d604af4 100644 --- a/Documentation/media/uapi/v4l/vidioc-query-dv-timings.rst +++ b/Documentation/media/uapi/v4l/vidioc-query-dv-timings.rst @@ -39,16 +39,16 @@ 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. -Please note that 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`. -The reason is that new timings usually mean different buffer sizes as -well, and you cannot change buffer sizes on the fly. In general, -applications that receive the Source Change event will have to call -:ref:`VIDIOC_QUERY_DV_TIMINGS`, and if the detected timings are valid they -will have to stop streaming, set the new timings, allocate new buffers -and start streaming again. +.. 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`. + The reason is that new timings usually mean different buffer sizes as + well, and you cannot change buffer sizes on the fly. In general, + applications that receive the Source Change event will have to call + :ref:`VIDIOC_QUERY_DV_TIMINGS`, and if the detected timings are valid they + will have to stop streaming, set the new timings, allocate new buffers + and start streaming again. If the timings could not be detected because there was no signal, then ENOLINK is returned. If a signal was detected, but it was unstable and diff --git a/Documentation/media/uapi/v4l/vidioc-queryctrl.rst b/Documentation/media/uapi/v4l/vidioc-queryctrl.rst index 0f27e712eec9..4342aceddd57 100644 --- a/Documentation/media/uapi/v4l/vidioc-queryctrl.rst +++ b/Documentation/media/uapi/v4l/vidioc-queryctrl.rst @@ -82,10 +82,12 @@ fills the rest of the structure or returns an ``EINVAL`` error code when the ``id`` or ``index`` is invalid. Menu items are enumerated by calling ``VIDIOC_QUERYMENU`` with successive ``index`` values from struct :ref:`v4l2_queryctrl <v4l2-queryctrl>` ``minimum`` to ``maximum``, -inclusive. Note that 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. +inclusive. + +.. 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. See also the examples in :ref:`control`. @@ -184,9 +186,10 @@ See also the examples in :ref:`control`. - The default value of a ``V4L2_CTRL_TYPE_INTEGER``, ``_BOOLEAN``, ``_BITMASK``, ``_MENU`` or ``_INTEGER_MENU`` control. Not valid - for other types of controls. Note that drivers reset controls to - their default value only when the driver is first loaded, never - afterwards. + for other types of controls. + + .. note:: Drivers reset controls to their default value only when + the driver is first loaded, never afterwards. - .. row 8 @@ -301,9 +304,10 @@ See also the examples in :ref:`control`. - The default value of a ``V4L2_CTRL_TYPE_INTEGER``, ``_INTEGER64``, ``_BOOLEAN``, ``_BITMASK``, ``_MENU``, ``_INTEGER_MENU``, ``_U8`` - or ``_U16`` control. Not valid for other types of controls. Note - that drivers reset controls to their default value only when the - driver is first loaded, never afterwards. + or ``_U16`` control. Not valid for other types of controls. + + .. note:: Drivers reset controls to their default value only when + the driver is first loaded, never afterwards. - .. row 8 @@ -722,11 +726,12 @@ See also the examples in :ref:`control`. control changes continuously. A typical example would be the current gain value if the device is in auto-gain mode. In such a case the hardware calculates the gain value based on the lighting - conditions which can change over time. Note that 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. + conditions which can change over time. + + .. 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. - .. row 9 diff --git a/Documentation/media/uapi/v4l/vidioc-querystd.rst b/Documentation/media/uapi/v4l/vidioc-querystd.rst index 5bf62775c740..b4a4e222c7b0 100644 --- a/Documentation/media/uapi/v4l/vidioc-querystd.rst +++ b/Documentation/media/uapi/v4l/vidioc-querystd.rst @@ -43,16 +43,16 @@ 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. -Please note that 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 -:ref:`VIDIOC_QUERYSTD`. The reason is that a new video standard can mean -different buffer sizes as well, and you cannot change buffer sizes on -the fly. In general, applications that receive the Source Change event -will have to call :ref:`VIDIOC_QUERYSTD`, and if the detected video -standard is valid they will have to stop streaming, set the new -standard, allocate new buffers and start streaming again. +.. 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 + :ref:`VIDIOC_QUERYSTD`. The reason is that a new video standard can mean + different buffer sizes as well, and you cannot change buffer sizes on + the fly. In general, applications that receive the Source Change event + will have to call :ref:`VIDIOC_QUERYSTD`, and if the detected video + standard is valid they will have to stop streaming, set the new + standard, allocate new buffers and start streaming again. Return Value diff --git a/Documentation/media/uapi/v4l/vidioc-streamon.rst b/Documentation/media/uapi/v4l/vidioc-streamon.rst index e87500e608e1..bb23745ebcaf 100644 --- a/Documentation/media/uapi/v4l/vidioc-streamon.rst +++ b/Documentation/media/uapi/v4l/vidioc-streamon.rst @@ -76,10 +76,10 @@ 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 that 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. +.. 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. Return Value diff --git a/Documentation/media/uapi/v4l/vidioc-subdev-g-crop.rst b/Documentation/media/uapi/v4l/vidioc-subdev-g-crop.rst index 690034a391d3..ae802f1594e7 100644 --- a/Documentation/media/uapi/v4l/vidioc-subdev-g-crop.rst +++ b/Documentation/media/uapi/v4l/vidioc-subdev-g-crop.rst @@ -35,7 +35,7 @@ Arguments Description =========== - **Note** +.. note:: This is an :ref:`obsolete` interface and may be removed in the future. It is superseded by diff --git a/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst b/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst index a027f602de3d..3ed91c627702 100644 --- a/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst +++ b/Documentation/media/uapi/v4l/vidioc-subscribe-event.rst @@ -51,9 +51,11 @@ using the :ref:`VIDIOC_DQEVENT` ioctl. - ``type`` - - Type of the event, see :ref:`event-type`. Note that - ``V4L2_EVENT_ALL`` can be used with VIDIOC_UNSUBSCRIBE_EVENT for - unsubscribing all events at once. + - Type of the event, see :ref:`event-type`. + + .. note:: ``V4L2_EVENT_ALL`` can be used with + :ref:`VIDIOC_UNSUBSCRIBE_EVENT` for unsubscribing all events + at once. - .. row 2 |