1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _dv-controls: 5 6******************************* 7Digital Video Control Reference 8******************************* 9 10The Digital Video control class is intended to control receivers and 11transmitters for `VGA <http://en.wikipedia.org/wiki/Vga>`__, 12`DVI <http://en.wikipedia.org/wiki/Digital_Visual_Interface>`__ 13(Digital Visual Interface), HDMI (:ref:`hdmi`) and DisplayPort 14(:ref:`dp`). These controls are generally expected to be private to 15the receiver or transmitter subdevice that implements them, so they are 16only exposed on the ``/dev/v4l-subdev*`` device node. 17 18.. note:: 19 20 Note that these devices can have multiple input or output pads which are 21 hooked up to e.g. HDMI connectors. Even though the subdevice will 22 receive or transmit video from/to only one of those pads, the other pads 23 can still be active when it comes to EDID (Extended Display 24 Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital 25 Content Protection System, :ref:`hdcp`) processing, allowing the 26 device to do the fairly slow EDID/HDCP handling in advance. This allows 27 for quick switching between connectors. 28 29These pads appear in several of the controls in this section as 30bitmasks, one bit for each pad. Bit 0 corresponds to pad 0, bit 1 to pad 311, etc. The maximum value of the control is the set of valid pads. 32 33 34.. _dv-control-id: 35 36Digital Video Control IDs 37========================= 38 39``V4L2_CID_DV_CLASS (class)`` 40 The Digital Video class descriptor. 41 42``V4L2_CID_DV_TX_HOTPLUG (bitmask)`` 43 Many connectors have a hotplug pin which is high if EDID information 44 is available from the source. This control shows the state of the 45 hotplug pin as seen by the transmitter. Each bit corresponds to an 46 output pad on the transmitter. If an output pad does not have an 47 associated hotplug pin, then the bit for that pad will be 0. This 48 read-only control is applicable to DVI-D, HDMI and DisplayPort 49 connectors. 50 51``V4L2_CID_DV_TX_RXSENSE (bitmask)`` 52 Rx Sense is the detection of pull-ups on the TMDS clock lines. This 53 normally means that the sink has left/entered standby (i.e. the 54 transmitter can sense that the receiver is ready to receive video). 55 Each bit corresponds to an output pad on the transmitter. If an 56 output pad does not have an associated Rx Sense, then the bit for 57 that pad will be 0. This read-only control is applicable to DVI-D 58 and HDMI devices. 59 60``V4L2_CID_DV_TX_EDID_PRESENT (bitmask)`` 61 When the transmitter sees the hotplug signal from the receiver it 62 will attempt to read the EDID. If set, then the transmitter has read 63 at least the first block (= 128 bytes). Each bit corresponds to an 64 output pad on the transmitter. If an output pad does not support 65 EDIDs, then the bit for that pad will be 0. This read-only control 66 is applicable to VGA, DVI-A/D, HDMI and DisplayPort connectors. 67 68``V4L2_CID_DV_TX_MODE`` 69 (enum) 70 71enum v4l2_dv_tx_mode - 72 HDMI transmitters can transmit in DVI-D mode (just video) or in HDMI 73 mode (video + audio + auxiliary data). This control selects which 74 mode to use: V4L2_DV_TX_MODE_DVI_D or V4L2_DV_TX_MODE_HDMI. 75 This control is applicable to HDMI connectors. 76 77``V4L2_CID_DV_TX_RGB_RANGE`` 78 (enum) 79 80enum v4l2_dv_rgb_range - 81 Select the quantization range for RGB output. V4L2_DV_RANGE_AUTO 82 follows the RGB quantization range specified in the standard for the 83 video interface (ie. :ref:`cea861` for HDMI). 84 V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the 85 standard to be compatible with sinks that have not implemented the 86 standard correctly (unfortunately quite common for HDMI and DVI-D). 87 Full range allows all possible values to be used whereas limited 88 range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is 89 the number of bits per component. This control is applicable to VGA, 90 DVI-A/D, HDMI and DisplayPort connectors. 91 92``V4L2_CID_DV_TX_IT_CONTENT_TYPE`` 93 (enum) 94 95enum v4l2_dv_it_content_type - 96 Configures the IT Content Type of the transmitted video. This 97 information is sent over HDMI and DisplayPort connectors as part of 98 the AVI InfoFrame. The term 'IT Content' is used for content that 99 originates from a computer as opposed to content from a TV broadcast 100 or an analog source. The enum v4l2_dv_it_content_type defines 101 the possible content types: 102 103.. tabularcolumns:: |p{7.3cm}|p{10.2cm}| 104 105.. flat-table:: 106 :header-rows: 0 107 :stub-columns: 0 108 109 * - ``V4L2_DV_IT_CONTENT_TYPE_GRAPHICS`` 110 - Graphics content. Pixel data should be passed unfiltered and 111 without analog reconstruction. 112 * - ``V4L2_DV_IT_CONTENT_TYPE_PHOTO`` 113 - Photo content. The content is derived from digital still pictures. 114 The content should be passed through with minimal scaling and 115 picture enhancements. 116 * - ``V4L2_DV_IT_CONTENT_TYPE_CINEMA`` 117 - Cinema content. 118 * - ``V4L2_DV_IT_CONTENT_TYPE_GAME`` 119 - Game content. Audio and video latency should be minimized. 120 * - ``V4L2_DV_IT_CONTENT_TYPE_NO_ITC`` 121 - No IT Content information is available and the ITC bit in the AVI 122 InfoFrame is set to 0. 123 124 125 126``V4L2_CID_DV_RX_POWER_PRESENT (bitmask)`` 127 Detects whether the receiver receives power from the source (e.g. 128 HDMI carries 5V on one of the pins). This is often used to power an 129 eeprom which contains EDID information, such that the source can 130 read the EDID even if the sink is in standby/power off. Each bit 131 corresponds to an input pad on the receiver. If an input pad 132 cannot detect whether power is present, then the bit for that pad 133 will be 0. This read-only control is applicable to DVI-D, HDMI and 134 DisplayPort connectors. 135 136``V4L2_CID_DV_RX_RGB_RANGE`` 137 (enum) 138 139enum v4l2_dv_rgb_range - 140 Select the quantization range for RGB input. V4L2_DV_RANGE_AUTO 141 follows the RGB quantization range specified in the standard for the 142 video interface (ie. :ref:`cea861` for HDMI). 143 V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the 144 standard to be compatible with sources that have not implemented the 145 standard correctly (unfortunately quite common for HDMI and DVI-D). 146 Full range allows all possible values to be used whereas limited 147 range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is 148 the number of bits per component. This control is applicable to VGA, 149 DVI-A/D, HDMI and DisplayPort connectors. 150 151``V4L2_CID_DV_RX_IT_CONTENT_TYPE`` 152 (enum) 153 154enum v4l2_dv_it_content_type - 155 Reads the IT Content Type of the received video. This information is 156 sent over HDMI and DisplayPort connectors as part of the AVI 157 InfoFrame. The term 'IT Content' is used for content that originates 158 from a computer as opposed to content from a TV broadcast or an 159 analog source. See ``V4L2_CID_DV_TX_IT_CONTENT_TYPE`` for the 160 available content types. 161