1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _VIDIOC_DBG_G_CHIP_INFO: 5 6**************************** 7ioctl VIDIOC_DBG_G_CHIP_INFO 8**************************** 9 10Name 11==== 12 13VIDIOC_DBG_G_CHIP_INFO - Identify the chips on a TV card 14 15Synopsis 16======== 17 18.. c:macro:: VIDIOC_DBG_G_CHIP_INFO 19 20``int ioctl(int fd, VIDIOC_DBG_G_CHIP_INFO, struct v4l2_dbg_chip_info *argp)`` 21 22Arguments 23========= 24 25``fd`` 26 File descriptor returned by :c:func:`open()`. 27 28``argp`` 29 Pointer to struct :c:type:`v4l2_dbg_chip_info`. 30 31Description 32=========== 33 34.. note:: 35 36 This is an :ref:`experimental` interface and may 37 change in the future. 38 39For driver debugging purposes this ioctl allows test applications to 40query the driver about the chips present on the TV card. Regular 41applications must not use it. When you found a chip specific bug, please 42contact the linux-media mailing list 43(`https://linuxtv.org/lists.php <https://linuxtv.org/lists.php>`__) 44so it can be fixed. 45 46Additionally the Linux kernel must be compiled with the 47``CONFIG_VIDEO_ADV_DEBUG`` option to enable this ioctl. 48 49To query the driver applications must initialize the ``match.type`` and 50``match.addr`` or ``match.name`` fields of a struct 51:c:type:`v4l2_dbg_chip_info` and call 52:ref:`VIDIOC_DBG_G_CHIP_INFO` with a pointer to this structure. On success 53the driver stores information about the selected chip in the ``name`` 54and ``flags`` fields. 55 56When ``match.type`` is ``V4L2_CHIP_MATCH_BRIDGE``, ``match.addr`` 57selects the nth bridge 'chip' on the TV card. You can enumerate all 58chips by starting at zero and incrementing ``match.addr`` by one until 59:ref:`VIDIOC_DBG_G_CHIP_INFO` fails with an ``EINVAL`` error code. The number 60zero always selects the bridge chip itself, e. g. the chip connected to 61the PCI or USB bus. Non-zero numbers identify specific parts of the 62bridge chip such as an AC97 register block. 63 64When ``match.type`` is ``V4L2_CHIP_MATCH_SUBDEV``, ``match.addr`` 65selects the nth sub-device. This allows you to enumerate over all 66sub-devices. 67 68On success, the ``name`` field will contain a chip name and the 69``flags`` field will contain ``V4L2_CHIP_FL_READABLE`` if the driver 70supports reading registers from the device or ``V4L2_CHIP_FL_WRITABLE`` 71if the driver supports writing registers to the device. 72 73We recommended the v4l2-dbg utility over calling this ioctl directly. It 74is available from the LinuxTV v4l-dvb repository; see 75`https://linuxtv.org/repo/ <https://linuxtv.org/repo/>`__ for access 76instructions. 77 78.. tabularcolumns:: |p{3.5cm}|p{3.5cm}|p{3.5cm}|p{6.6cm}| 79 80.. _name-v4l2-dbg-match: 81 82.. flat-table:: struct v4l2_dbg_match 83 :header-rows: 0 84 :stub-columns: 0 85 :widths: 1 1 2 86 87 * - __u32 88 - ``type`` 89 - See :ref:`name-chip-match-types` for a list of possible types. 90 * - union { 91 - (anonymous) 92 * - __u32 93 - ``addr`` 94 - Match a chip by this number, interpreted according to the ``type`` 95 field. 96 * - char 97 - ``name[32]`` 98 - Match a chip by this name, interpreted according to the ``type`` 99 field. Currently unused. 100 * - } 101 - 102 103 104.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| 105 106.. c:type:: v4l2_dbg_chip_info 107 108.. flat-table:: struct v4l2_dbg_chip_info 109 :header-rows: 0 110 :stub-columns: 0 111 :widths: 1 1 2 112 113 * - struct v4l2_dbg_match 114 - ``match`` 115 - How to match the chip, see :ref:`name-v4l2-dbg-match`. 116 * - char 117 - ``name[32]`` 118 - The name of the chip. 119 * - __u32 120 - ``flags`` 121 - Set by the driver. If ``V4L2_CHIP_FL_READABLE`` is set, then the 122 driver supports reading registers from the device. If 123 ``V4L2_CHIP_FL_WRITABLE`` is set, then it supports writing 124 registers. 125 * - __u32 126 - ``reserved[8]`` 127 - Reserved fields, both application and driver must set these to 0. 128 129 130.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}| 131 132.. _name-chip-match-types: 133 134.. flat-table:: Chip Match Types 135 :header-rows: 0 136 :stub-columns: 0 137 :widths: 3 1 4 138 139 * - ``V4L2_CHIP_MATCH_BRIDGE`` 140 - 0 141 - Match the nth chip on the card, zero for the bridge chip. Does not 142 match sub-devices. 143 * - ``V4L2_CHIP_MATCH_SUBDEV`` 144 - 4 145 - Match the nth sub-device. 146 147Return Value 148============ 149 150On success 0 is returned, on error -1 and the ``errno`` variable is set 151appropriately. The generic error codes are described at the 152:ref:`Generic Error Codes <gen-errors>` chapter. 153 154EINVAL 155 The ``match_type`` is invalid or no device could be matched. 156