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diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-dv.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-dv.rst new file mode 100644 index 000000000..d2794e03a --- /dev/null +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-dv.rst @@ -0,0 +1,159 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later + +.. _dv-controls: + +******************************* +Digital Video Control Reference +******************************* + +The Digital Video control class is intended to control receivers and +transmitters for `VGA <http://en.wikipedia.org/wiki/Vga>`__, +`DVI <http://en.wikipedia.org/wiki/Digital_Visual_Interface>`__ +(Digital Visual Interface), HDMI (:ref:`hdmi`) and DisplayPort +(:ref:`dp`). These controls are generally expected to be private to +the receiver or transmitter subdevice that implements them, so they are +only exposed on the ``/dev/v4l-subdev*`` device node. + +.. 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 +1, etc. The maximum value of the control is the set of valid pads. + + +.. _dv-control-id: + +Digital Video Control IDs +========================= + +``V4L2_CID_DV_CLASS (class)`` + The Digital Video class descriptor. + +``V4L2_CID_DV_TX_HOTPLUG (bitmask)`` + Many connectors have a hotplug pin which is high if EDID information + is available from the source. This control shows the state of the + hotplug pin as seen by the transmitter. Each bit corresponds to an + output pad on the transmitter. If an output pad does not have an + associated hotplug pin, then the bit for that pad will be 0. This + read-only control is applicable to DVI-D, HDMI and DisplayPort + connectors. + +``V4L2_CID_DV_TX_RXSENSE (bitmask)`` + Rx Sense is the detection of pull-ups on the TMDS clock lines. This + normally means that the sink has left/entered standby (i.e. the + transmitter can sense that the receiver is ready to receive video). + Each bit corresponds to an output pad on the transmitter. If an + output pad does not have an associated Rx Sense, then the bit for + that pad will be 0. This read-only control is applicable to DVI-D + and HDMI devices. + +``V4L2_CID_DV_TX_EDID_PRESENT (bitmask)`` + When the transmitter sees the hotplug signal from the receiver it + will attempt to read the EDID. If set, then the transmitter has read + at least the first block (= 128 bytes). Each bit corresponds to an + output pad on the transmitter. If an output pad does not support + EDIDs, then the bit for that pad will be 0. This read-only control + is applicable to VGA, DVI-A/D, HDMI and DisplayPort connectors. + +``V4L2_CID_DV_TX_MODE`` + (enum) + +enum v4l2_dv_tx_mode - + HDMI transmitters can transmit in DVI-D mode (just video) or in HDMI + mode (video + audio + auxiliary data). This control selects which + mode to use: V4L2_DV_TX_MODE_DVI_D or V4L2_DV_TX_MODE_HDMI. + This control is applicable to HDMI connectors. + +``V4L2_CID_DV_TX_RGB_RANGE`` + (enum) + +enum v4l2_dv_rgb_range - + Select the quantization range for RGB output. V4L2_DV_RANGE_AUTO + follows the RGB quantization range specified in the standard for the + video interface (ie. :ref:`cea861` for HDMI). + V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the + standard to be compatible with sinks that have not implemented the + standard correctly (unfortunately quite common for HDMI and DVI-D). + Full range allows all possible values to be used whereas limited + range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is + the number of bits per component. This control is applicable to VGA, + DVI-A/D, HDMI and DisplayPort connectors. + +``V4L2_CID_DV_TX_IT_CONTENT_TYPE`` + (enum) + +enum v4l2_dv_it_content_type - + Configures the IT Content Type of the transmitted video. This + information is sent over HDMI and DisplayPort connectors as part of + the AVI InfoFrame. The term 'IT Content' is used for content that + originates from a computer as opposed to content from a TV broadcast + or an analog source. The enum v4l2_dv_it_content_type defines + the possible content types: + +.. tabularcolumns:: |p{7.3cm}|p{10.2cm}| + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + + * - ``V4L2_DV_IT_CONTENT_TYPE_GRAPHICS`` + - Graphics content. Pixel data should be passed unfiltered and + without analog reconstruction. + * - ``V4L2_DV_IT_CONTENT_TYPE_PHOTO`` + - Photo content. The content is derived from digital still pictures. + The content should be passed through with minimal scaling and + picture enhancements. + * - ``V4L2_DV_IT_CONTENT_TYPE_CINEMA`` + - Cinema content. + * - ``V4L2_DV_IT_CONTENT_TYPE_GAME`` + - Game content. Audio and video latency should be minimized. + * - ``V4L2_DV_IT_CONTENT_TYPE_NO_ITC`` + - No IT Content information is available and the ITC bit in the AVI + InfoFrame is set to 0. + + + +``V4L2_CID_DV_RX_POWER_PRESENT (bitmask)`` + Detects whether the receiver receives power from the source (e.g. + HDMI carries 5V on one of the pins). This is often used to power an + eeprom which contains EDID information, such that the source can + read the EDID even if the sink is in standby/power off. Each bit + corresponds to an input pad on the receiver. If an input pad + cannot detect whether power is present, then the bit for that pad + will be 0. This read-only control is applicable to DVI-D, HDMI and + DisplayPort connectors. + +``V4L2_CID_DV_RX_RGB_RANGE`` + (enum) + +enum v4l2_dv_rgb_range - + Select the quantization range for RGB input. V4L2_DV_RANGE_AUTO + follows the RGB quantization range specified in the standard for the + video interface (ie. :ref:`cea861` for HDMI). + V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the + standard to be compatible with sources that have not implemented the + standard correctly (unfortunately quite common for HDMI and DVI-D). + Full range allows all possible values to be used whereas limited + range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is + the number of bits per component. This control is applicable to VGA, + DVI-A/D, HDMI and DisplayPort connectors. + +``V4L2_CID_DV_RX_IT_CONTENT_TYPE`` + (enum) + +enum v4l2_dv_it_content_type - + Reads the IT Content Type of the received video. This information is + sent over HDMI and DisplayPort connectors as part of the AVI + InfoFrame. The term 'IT Content' is used for content that originates + from a computer as opposed to content from a TV broadcast or an + analog source. See ``V4L2_CID_DV_TX_IT_CONTENT_TYPE`` for the + available content types. |