@@ -78,6 +78,7 @@ Function Reference
vidioc-subdev-g-fmt
vidioc-subdev-g-frame-interval
vidioc-subdev-g-selection
+ vidioc-subdev-querycap
vidioc-subscribe-event
func-mmap
func-munmap
new file mode 100644
@@ -0,0 +1,112 @@
+.. Permission is granted to copy, distribute and/or modify this
+.. document under the terms of the GNU Free Documentation License,
+.. Version 1.1 or any later version published by the Free Software
+.. Foundation, with no Invariant Sections, no Front-Cover Texts
+.. and no Back-Cover Texts. A copy of the license is included at
+.. Documentation/userspace-api/media/fdl-appendix.rst.
+..
+.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
+
+.. _VIDIOC_SUBDEV_QUERYCAP:
+
+****************************
+ioctl VIDIOC_SUBDEV_QUERYCAP
+****************************
+
+Name
+====
+
+VIDIOC_SUBDEV_QUERYCAP - Query sub-device capabilities
+
+
+Synopsis
+========
+
+.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_QUERYCAP, struct v4l2_subdev_capability *argp )
+ :name: VIDIOC_SUBDEV_QUERYCAP
+
+
+Arguments
+=========
+
+``fd``
+ File descriptor returned by :ref:`open() <func-open>`.
+
+``argp``
+ Pointer to struct :c:type:`v4l2_subdev_capability`.
+
+
+Description
+===========
+
+All V4L2 sub-devices support the ``VIDIOC_SUBDEV_QUERYCAP`` ioctl. It is used to
+identify kernel devices compatible with this specification and to obtain
+information about driver and hardware capabilities. The ioctl takes a pointer to
+a struct :c:type:`v4l2_subdev_capability` which is filled by the driver. When
+the driver is not compatible with this specification the ioctl returns
+``ENOTTY`` error code.
+
+.. tabularcolumns:: |p{1.5cm}|p{2.5cm}|p{13cm}|
+
+.. c:type:: v4l2_subdev_capability
+
+.. flat-table:: struct v4l2_subdev_capability
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 3 4 20
+
+ * - __u32
+ - ``version``
+ - Version number of the driver.
+
+ The version reported is provided by the V4L2 subsystem following the
+ kernel numbering scheme. However, it may not always return the same
+ version as the kernel if, for example, a stable or
+ distribution-modified kernel uses the V4L2 stack from a newer kernel.
+
+ The version number is formatted using the ``KERNEL_VERSION()``
+ macro:
+ * - :cspan:`2`
+
+ ``#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))``
+
+ ``__u32 version = KERNEL_VERSION(0, 8, 1);``
+
+ ``printf ("Version: %u.%u.%u\\n",``
+
+ ``(version >> 16) & 0xFF, (version >> 8) & 0xFF, version & 0xFF);``
+ * - __u32
+ - ``capabilities``
+ - Sub-device capabilities of the opened device, see
+ :ref:`subdevice-capabilities`.
+ * - __u32
+ - ``reserved``\ [14]
+ - Reserved for future extensions. Set to 0 by the V4L2 core.
+
+.. tabularcolumns:: |p{6cm}|p{2.2cm}|p{8.8cm}|
+
+.. _subdevice-capabilities:
+
+.. cssclass:: longtable
+
+.. flat-table:: Sub-Device Capabilities Flags
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 3 1 4
+
+ * - V4L2_SUBDEV_CAP_RO_SUBDEV
+ - 0x00000001
+ - The sub-device device node is registered in read-only mode.
+ Access to the sub-device ioctls that modify the device state is
+ restricted. Refer to each individual subdevice ioctl documentation
+ for a description of which restrictions apply to a read-only sub-device.
+
+Return Value
+============
+
+On success 0 is returned, on error -1 and the ``errno`` variable is set
+appropriately. The generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.
+
+ENOTTY
+ The device node is not a V4L2 sub-device.