VIDIOC_DBG_G_CHIP_INFO — Identify the chips on a TV card
File descriptor returned by
This is an experimental interface and may change in the future.
For driver debugging purposes this ioctl allows test applications to query the driver about the chips present on the TV card. Regular applications must not use it. When you found a chip specific bug, please contact the linux-media mailing list (https://linuxtv.org/lists.php) so it can be fixed.
Additionally the Linux kernel must be compiled with the
CONFIG_VIDEO_ADV_DEBUG option to enable this ioctl.
To query the driver applications must initialize the
fields of a struct v4l2_dbg_chip_info
VIDIOC_DBG_G_CHIP_INFO with a pointer to
this structure. On success the driver stores information about the
selected chip in the
match.addr selects the nth bridge 'chip'
on the TV card. You can enumerate all chips by starting at zero and
match.addr by one until
VIDIOC_DBG_G_CHIP_INFO fails with an EINVAL error code.
The number zero always selects the bridge chip itself, e. g. the chip
connected to the PCI or USB bus. Non-zero numbers identify specific
parts of the bridge chip such as an AC97 register block.
match.addr selects the nth sub-device. This
allows you to enumerate over all sub-devices.
On success, the
name field will
contain a chip name and the
flags field will
V4L2_CHIP_FL_READABLE if the driver supports
reading registers from the device or
if the driver supports writing registers to the device.
We recommended the v4l2-dbg utility over calling this ioctl directly. It is available from the LinuxTV v4l-dvb repository; see https://linuxtv.org/repo/ for access instructions.
Table A.4. struct v4l2_dbg_match
|__u32||See Table A.6, “Chip Match Types” for a list of possible types.|
|__u32||Match a chip by this number, interpreted according
to the |
|char||Match a chip by this name, interpreted according
to the |
Table A.5. struct v4l2_dbg_chip_info
|struct v4l2_dbg_match||How to match the chip, see Table A.4, “struct v4l2_dbg_match”.|
|char||The name of the chip.|
|__u32||Set by the driver. If |
|__u32||Reserved fields, both application and driver must set these to 0.|
Table A.6. Chip Match Types
|0||Match the nth chip on the card, zero for the bridge chip. Does not match sub-devices.|
|4||Match the nth sub-device.|
On success 0 is returned, on error -1 and the
errno variable is set appropriately. The generic error codes are described at the Generic Error Codes chapter.
match_type is invalid or
no device could be matched.