1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _VIDIOC_SUBDEV_QUERYCAP: 5 6**************************** 7ioctl VIDIOC_SUBDEV_QUERYCAP 8**************************** 9 10Name 11==== 12 13VIDIOC_SUBDEV_QUERYCAP - Query sub-device capabilities 14 15Synopsis 16======== 17 18.. c:macro:: VIDIOC_SUBDEV_QUERYCAP 19 20``int ioctl(int fd, VIDIOC_SUBDEV_QUERYCAP, struct v4l2_subdev_capability *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_subdev_capability`. 30 31Description 32=========== 33 34All V4L2 sub-devices support the ``VIDIOC_SUBDEV_QUERYCAP`` ioctl. It is used to 35identify kernel devices compatible with this specification and to obtain 36information about driver and hardware capabilities. The ioctl takes a pointer to 37a struct :c:type:`v4l2_subdev_capability` which is filled by the driver. When 38the driver is not compatible with this specification the ioctl returns 39``ENOTTY`` error code. 40 41.. tabularcolumns:: |p{1.5cm}|p{2.9cm}|p{12.9cm}| 42 43.. c:type:: v4l2_subdev_capability 44 45.. flat-table:: struct v4l2_subdev_capability 46 :header-rows: 0 47 :stub-columns: 0 48 :widths: 3 4 20 49 50 * - __u32 51 - ``version`` 52 - Version number of the driver. 53 54 The version reported is provided by the V4L2 subsystem following the 55 kernel numbering scheme. However, it may not always return the same 56 version as the kernel if, for example, a stable or 57 distribution-modified kernel uses the V4L2 stack from a newer kernel. 58 59 The version number is formatted using the ``KERNEL_VERSION()`` 60 macro: 61 * - :cspan:`2` 62 63 ``#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))`` 64 65 ``__u32 version = KERNEL_VERSION(0, 8, 1);`` 66 67 ``printf ("Version: %u.%u.%u\\n",`` 68 69 ``(version >> 16) & 0xFF, (version >> 8) & 0xFF, version & 0xFF);`` 70 * - __u32 71 - ``capabilities`` 72 - Sub-device capabilities of the opened device, see 73 :ref:`subdevice-capabilities`. 74 * - __u32 75 - ``reserved``\ [14] 76 - Reserved for future extensions. Set to 0 by the V4L2 core. 77 78.. tabularcolumns:: |p{6.8cm}|p{2.4cm}|p{8.1cm}| 79 80.. _subdevice-capabilities: 81 82.. cssclass:: longtable 83 84.. flat-table:: Sub-Device Capabilities Flags 85 :header-rows: 0 86 :stub-columns: 0 87 :widths: 3 1 4 88 89 * - V4L2_SUBDEV_CAP_RO_SUBDEV 90 - 0x00000001 91 - The sub-device device node is registered in read-only mode. 92 Access to the sub-device ioctls that modify the device state is 93 restricted. Refer to each individual subdevice ioctl documentation 94 for a description of which restrictions apply to a read-only sub-device. 95 96Return Value 97============ 98 99On success 0 is returned, on error -1 and the ``errno`` variable is set 100appropriately. The generic error codes are described at the 101:ref:`Generic Error Codes <gen-errors>` chapter. 102 103ENOTTY 104 The device node is not a V4L2 sub-device. 105