Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 603 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst b/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst
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@@ -0,0 +1,603 @@
+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: V4L
+
+.. _VIDIOC_QUERYCTRL:
+
+*******************************************************************
+ioctls VIDIOC_QUERYCTRL, VIDIOC_QUERY_EXT_CTRL and VIDIOC_QUERYMENU
+*******************************************************************
+
+Name
+====
+
+VIDIOC_QUERYCTRL - VIDIOC_QUERY_EXT_CTRL - VIDIOC_QUERYMENU - Enumerate controls and menu control items
+
+Synopsis
+========
+
+``int ioctl(int fd, int VIDIOC_QUERYCTRL, struct v4l2_queryctrl *argp)``
+
+.. c:macro:: VIDIOC_QUERY_EXT_CTRL
+
+``int ioctl(int fd, VIDIOC_QUERY_EXT_CTRL, struct v4l2_query_ext_ctrl *argp)``
+
+.. c:macro:: VIDIOC_QUERYMENU
+
+``int ioctl(int fd, VIDIOC_QUERYMENU, struct v4l2_querymenu *argp)``
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :c:func:`open()`.
+
+``argp``
+    Pointer to struct :c:type:`v4l2_queryctrl`, :c:type:`v4l2_query_ext_ctrl`
+    or :c:type:`v4l2_querymenu` (depending on the ioctl).
+
+Description
+===========
+
+To query the attributes of a control applications set the ``id`` field
+of a struct :ref:`v4l2_queryctrl <v4l2-queryctrl>` and call the
+``VIDIOC_QUERYCTRL`` ioctl with a pointer to this structure. The driver
+fills the rest of the structure or returns an ``EINVAL`` error code when the
+``id`` is invalid.
+
+It is possible to enumerate controls by calling ``VIDIOC_QUERYCTRL``
+with successive ``id`` values starting from ``V4L2_CID_BASE`` up to and
+exclusive ``V4L2_CID_LASTP1``. Drivers may return ``EINVAL`` if a control in
+this range is not supported. Further applications can enumerate private
+controls, which are not defined in this specification, by starting at
+``V4L2_CID_PRIVATE_BASE`` and incrementing ``id`` until the driver
+returns ``EINVAL``.
+
+In both cases, when the driver sets the ``V4L2_CTRL_FLAG_DISABLED`` flag
+in the ``flags`` field this control is permanently disabled and should
+be ignored by the application. [#f1]_
+
+When the application ORs ``id`` with ``V4L2_CTRL_FLAG_NEXT_CTRL`` the
+driver returns the next supported non-compound control, or ``EINVAL`` if
+there is none. In addition, the ``V4L2_CTRL_FLAG_NEXT_COMPOUND`` flag
+can be specified to enumerate all compound controls (i.e. controls with
+type ≥ ``V4L2_CTRL_COMPOUND_TYPES`` and/or array control, in other words
+controls that contain more than one value). Specify both
+``V4L2_CTRL_FLAG_NEXT_CTRL`` and ``V4L2_CTRL_FLAG_NEXT_COMPOUND`` in
+order to enumerate all controls, compound or not. Drivers which do not
+support these flags yet always return ``EINVAL``.
+
+The ``VIDIOC_QUERY_EXT_CTRL`` ioctl was introduced in order to better
+support controls that can use compound types, and to expose additional
+control information that cannot be returned in struct
+:ref:`v4l2_queryctrl <v4l2-queryctrl>` since that structure is full.
+
+``VIDIOC_QUERY_EXT_CTRL`` is used in the same way as
+``VIDIOC_QUERYCTRL``, except that the ``reserved`` array must be zeroed
+as well.
+
+Additional information is required for menu controls: the names of the
+menu items. To query them applications set the ``id`` and ``index``
+fields of struct :ref:`v4l2_querymenu <v4l2-querymenu>` and call the
+``VIDIOC_QUERYMENU`` ioctl with a pointer to this structure. The driver
+fills the rest of the structure or returns an ``EINVAL`` error code when the
+``id`` or ``index`` is invalid. Menu items are enumerated by calling
+``VIDIOC_QUERYMENU`` with successive ``index`` values from struct
+:ref:`v4l2_queryctrl <v4l2-queryctrl>` ``minimum`` to ``maximum``,
+inclusive.
+
+.. note::
+
+   It is possible for ``VIDIOC_QUERYMENU`` to return
+   an ``EINVAL`` error code for some indices between ``minimum`` and
+   ``maximum``. In that case that particular menu item is not supported by
+   this driver. Also note that the ``minimum`` value is not necessarily 0.
+
+See also the examples in :ref:`control`.
+
+.. tabularcolumns:: |p{1.2cm}|p{3.6cm}|p{12.7cm}|
+
+.. _v4l2-queryctrl:
+
+.. cssclass:: longtable
+
+.. flat-table:: struct v4l2_queryctrl
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - __u32
+      - ``id``
+      - Identifies the control, set by the application. See
+	:ref:`control-id` for predefined IDs. When the ID is ORed with
+	V4L2_CTRL_FLAG_NEXT_CTRL the driver clears the flag and
+	returns the first control with a higher ID. Drivers which do not
+	support this flag yet always return an ``EINVAL`` error code.
+    * - __u32
+      - ``type``
+      - Type of control, see :c:type:`v4l2_ctrl_type`.
+    * - __u8
+      - ``name``\ [32]
+      - Name of the control, a NUL-terminated ASCII string. This
+	information is intended for the user.
+    * - __s32
+      - ``minimum``
+      - Minimum value, inclusive. This field gives a lower bound for the
+	control. See enum :c:type:`v4l2_ctrl_type` how
+	the minimum value is to be used for each possible control type.
+	Note that this a signed 32-bit value.
+    * - __s32
+      - ``maximum``
+      - Maximum value, inclusive. This field gives an upper bound for the
+	control. See enum :c:type:`v4l2_ctrl_type` how
+	the maximum value is to be used for each possible control type.
+	Note that this a signed 32-bit value.
+    * - __s32
+      - ``step``
+      - This field gives a step size for the control. See enum
+	:c:type:`v4l2_ctrl_type` how the step value is
+	to be used for each possible control type. Note that this an
+	unsigned 32-bit value.
+
+	Generally drivers should not scale hardware control values. It may
+	be necessary for example when the ``name`` or ``id`` imply a
+	particular unit and the hardware actually accepts only multiples
+	of said unit. If so, drivers must take care values are properly
+	rounded when scaling, such that errors will not accumulate on
+	repeated read-write cycles.
+
+	This field gives the smallest change of an integer control
+	actually affecting hardware. Often the information is needed when
+	the user can change controls by keyboard or GUI buttons, rather
+	than a slider. When for example a hardware register accepts values
+	0-511 and the driver reports 0-65535, step should be 128.
+
+	Note that although signed, the step value is supposed to be always
+	positive.
+    * - __s32
+      - ``default_value``
+      - The default value of a ``V4L2_CTRL_TYPE_INTEGER``, ``_BOOLEAN``,
+	``_BITMASK``, ``_MENU`` or ``_INTEGER_MENU`` control. Not valid
+	for other types of controls.
+
+	.. note::
+
+	   Drivers reset controls to their default value only when
+	   the driver is first loaded, never afterwards.
+    * - __u32
+      - ``flags``
+      - Control flags, see :ref:`control-flags`.
+    * - __u32
+      - ``reserved``\ [2]
+      - Reserved for future extensions. Drivers must set the array to
+	zero.
+
+
+.. tabularcolumns:: |p{1.2cm}|p{5.0cm}|p{11.3cm}|
+
+.. _v4l2-query-ext-ctrl:
+
+.. cssclass:: longtable
+
+.. flat-table:: struct v4l2_query_ext_ctrl
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - __u32
+      - ``id``
+      - Identifies the control, set by the application. See
+	:ref:`control-id` for predefined IDs. When the ID is ORed with
+	``V4L2_CTRL_FLAG_NEXT_CTRL`` the driver clears the flag and
+	returns the first non-compound control with a higher ID. When the
+	ID is ORed with ``V4L2_CTRL_FLAG_NEXT_COMPOUND`` the driver clears
+	the flag and returns the first compound control with a higher ID.
+	Set both to get the first control (compound or not) with a higher
+	ID.
+    * - __u32
+      - ``type``
+      - Type of control, see :c:type:`v4l2_ctrl_type`.
+    * - char
+      - ``name``\ [32]
+      - Name of the control, a NUL-terminated ASCII string. This
+	information is intended for the user.
+    * - __s64
+      - ``minimum``
+      - Minimum value, inclusive. This field gives a lower bound for the
+	control. See enum :c:type:`v4l2_ctrl_type` how
+	the minimum value is to be used for each possible control type.
+	Note that this a signed 64-bit value.
+    * - __s64
+      - ``maximum``
+      - Maximum value, inclusive. This field gives an upper bound for the
+	control. See enum :c:type:`v4l2_ctrl_type` how
+	the maximum value is to be used for each possible control type.
+	Note that this a signed 64-bit value.
+    * - __u64
+      - ``step``
+      - This field gives a step size for the control. See enum
+	:c:type:`v4l2_ctrl_type` how the step value is
+	to be used for each possible control type. Note that this an
+	unsigned 64-bit value.
+
+	Generally drivers should not scale hardware control values. It may
+	be necessary for example when the ``name`` or ``id`` imply a
+	particular unit and the hardware actually accepts only multiples
+	of said unit. If so, drivers must take care values are properly
+	rounded when scaling, such that errors will not accumulate on
+	repeated read-write cycles.
+
+	This field gives the smallest change of an integer control
+	actually affecting hardware. Often the information is needed when
+	the user can change controls by keyboard or GUI buttons, rather
+	than a slider. When for example a hardware register accepts values
+	0-511 and the driver reports 0-65535, step should be 128.
+    * - __s64
+      - ``default_value``
+      - The default value of a ``V4L2_CTRL_TYPE_INTEGER``, ``_INTEGER64``,
+	``_BOOLEAN``, ``_BITMASK``, ``_MENU``, ``_INTEGER_MENU``, ``_U8``
+	or ``_U16`` control. Not valid for other types of controls.
+
+	.. note::
+
+	   Drivers reset controls to their default value only when
+	   the driver is first loaded, never afterwards.
+    * - __u32
+      - ``flags``
+      - Control flags, see :ref:`control-flags`.
+    * - __u32
+      - ``elem_size``
+      - The size in bytes of a single element of the array. Given a char
+	pointer ``p`` to a 3-dimensional array you can find the position
+	of cell ``(z, y, x)`` as follows:
+	``p + ((z * dims[1] + y) * dims[0] + x) * elem_size``.
+	``elem_size`` is always valid, also when the control isn't an
+	array. For string controls ``elem_size`` is equal to
+	``maximum + 1``.
+    * - __u32
+      - ``elems``
+      - The number of elements in the N-dimensional array. If this control
+	is not an array, then ``elems`` is 1. The ``elems`` field can
+	never be 0.
+    * - __u32
+      - ``nr_of_dims``
+      - The number of dimension in the N-dimensional array. If this
+	control is not an array, then this field is 0.
+    * - __u32
+      - ``dims[V4L2_CTRL_MAX_DIMS]``
+      - The size of each dimension. The first ``nr_of_dims`` elements of
+	this array must be non-zero, all remaining elements must be zero.
+    * - __u32
+      - ``reserved``\ [32]
+      - Reserved for future extensions. Applications and drivers must set
+	the array to zero.
+
+
+.. tabularcolumns:: |p{1.2cm}|p{1.0cm}|p{1.7cm}|p{13.0cm}|
+
+.. _v4l2-querymenu:
+
+.. flat-table:: struct v4l2_querymenu
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - __u32
+      - ``id``
+      - Identifies the control, set by the application from the respective
+	struct :ref:`v4l2_queryctrl <v4l2-queryctrl>` ``id``.
+    * - __u32
+      - ``index``
+      - Index of the menu item, starting at zero, set by the application.
+    * - union {
+      - (anonymous)
+    * - __u8
+      - ``name``\ [32]
+      - Name of the menu item, a NUL-terminated ASCII string. This
+	information is intended for the user. This field is valid for
+	``V4L2_CTRL_TYPE_MENU`` type controls.
+    * - __s64
+      - ``value``
+      - Value of the integer menu item. This field is valid for
+	``V4L2_CTRL_TYPE_INTEGER_MENU`` type controls.
+    * - }
+      -
+    * - __u32
+      - ``reserved``
+      - Reserved for future extensions. Drivers must set the array to
+	zero.
+
+
+.. tabularcolumns:: |p{5.8cm}|p{1.4cm}|p{1.0cm}|p{1.4cm}|p{6.9cm}|
+
+.. c:type:: v4l2_ctrl_type
+
+.. cssclass:: longtable
+
+.. flat-table:: enum v4l2_ctrl_type
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       30 5 5 5 55
+
+    * - Type
+      - ``minimum``
+      - ``step``
+      - ``maximum``
+      - Description
+    * - ``V4L2_CTRL_TYPE_INTEGER``
+      - any
+      - any
+      - any
+      - An integer-valued control ranging from minimum to maximum
+	inclusive. The step value indicates the increment between values.
+    * - ``V4L2_CTRL_TYPE_BOOLEAN``
+      - 0
+      - 1
+      - 1
+      - A boolean-valued control. Zero corresponds to "disabled", and one
+	means "enabled".
+    * - ``V4L2_CTRL_TYPE_MENU``
+      - ≥ 0
+      - 1
+      - N-1
+      - The control has a menu of N choices. The names of the menu items
+	can be enumerated with the ``VIDIOC_QUERYMENU`` ioctl.
+    * - ``V4L2_CTRL_TYPE_INTEGER_MENU``
+      - ≥ 0
+      - 1
+      - N-1
+      - The control has a menu of N choices. The values of the menu items
+	can be enumerated with the ``VIDIOC_QUERYMENU`` ioctl. This is
+	similar to ``V4L2_CTRL_TYPE_MENU`` except that instead of strings,
+	the menu items are signed 64-bit integers.
+    * - ``V4L2_CTRL_TYPE_BITMASK``
+      - 0
+      - n/a
+      - any
+      - A bitmask field. The maximum value is the set of bits that can be
+	used, all other bits are to be 0. The maximum value is interpreted
+	as a __u32, allowing the use of bit 31 in the bitmask.
+    * - ``V4L2_CTRL_TYPE_BUTTON``
+      - 0
+      - 0
+      - 0
+      - A control which performs an action when set. Drivers must ignore
+	the value passed with ``VIDIOC_S_CTRL`` and return an ``EACCES`` error
+	code on a ``VIDIOC_G_CTRL`` attempt.
+    * - ``V4L2_CTRL_TYPE_INTEGER64``
+      - any
+      - any
+      - any
+      - A 64-bit integer valued control. Minimum, maximum and step size
+	cannot be queried using ``VIDIOC_QUERYCTRL``. Only
+	``VIDIOC_QUERY_EXT_CTRL`` can retrieve the 64-bit min/max/step
+	values, they should be interpreted as n/a when using
+	``VIDIOC_QUERYCTRL``.
+    * - ``V4L2_CTRL_TYPE_STRING``
+      - ≥ 0
+      - ≥ 1
+      - ≥ 0
+      - The minimum and maximum string lengths. The step size means that
+	the string must be (minimum + N * step) characters long for N ≥ 0.
+	These lengths do not include the terminating zero, so in order to
+	pass a string of length 8 to
+	:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` you need to
+	set the ``size`` field of struct
+	:c:type:`v4l2_ext_control` to 9. For
+	:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` you can set
+	the ``size`` field to ``maximum`` + 1. Which character encoding is
+	used will depend on the string control itself and should be part
+	of the control documentation.
+    * - ``V4L2_CTRL_TYPE_CTRL_CLASS``
+      - n/a
+      - n/a
+      - n/a
+      - This is not a control. When ``VIDIOC_QUERYCTRL`` is called with a
+	control ID equal to a control class code (see :ref:`ctrl-class`)
+	+ 1, the ioctl returns the name of the control class and this
+	control type. Older drivers which do not support this feature
+	return an ``EINVAL`` error code.
+    * - ``V4L2_CTRL_TYPE_U8``
+      - any
+      - any
+      - any
+      - An unsigned 8-bit valued control ranging from minimum to maximum
+	inclusive. The step value indicates the increment between values.
+    * - ``V4L2_CTRL_TYPE_U16``
+      - any
+      - any
+      - any
+      - An unsigned 16-bit valued control ranging from minimum to maximum
+	inclusive. The step value indicates the increment between values.
+    * - ``V4L2_CTRL_TYPE_U32``
+      - any
+      - any
+      - any
+      - An unsigned 32-bit valued control ranging from minimum to maximum
+	inclusive. The step value indicates the increment between values.
+    * - ``V4L2_CTRL_TYPE_MPEG2_SLICE_PARAMS``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_mpeg2_slice_params`, containing MPEG-2
+	slice parameters for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_MPEG2_QUANTIZATION``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_mpeg2_quantization`, containing MPEG-2
+	quantization matrices for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_AREA``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_area`, containing the width and the height
+        of a rectangular area. Units depend on the use case.
+    * - ``V4L2_CTRL_TYPE_H264_SPS``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_h264_sps`, containing H264
+	sequence parameters for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_H264_PPS``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_h264_pps`, containing H264
+	picture parameters for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_H264_SCALING_MATRIX``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_h264_scaling_matrix`, containing H264
+	scaling matrices for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_H264_SLICE_PARAMS``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_h264_slice_params`, containing H264
+	slice parameters for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_H264_DECODE_PARAMS``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_h264_decode_params`, containing H264
+	decode parameters for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_HEVC_SPS``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_hevc_sps`, containing HEVC Sequence
+	Parameter Set for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_HEVC_PPS``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_hevc_pps`, containing HEVC Picture
+	Parameter Set for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_HEVC_SLICE_PARAMS``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_hevc_slice_params`, containing HEVC
+	slice parameters for stateless video decoders.
+
+.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}|
+
+.. _control-flags:
+
+.. cssclass:: longtable
+
+.. flat-table:: Control Flags
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       3 1 4
+
+    * - ``V4L2_CTRL_FLAG_DISABLED``
+      - 0x0001
+      - This control is permanently disabled and should be ignored by the
+	application. Any attempt to change the control will result in an
+	``EINVAL`` error code.
+    * - ``V4L2_CTRL_FLAG_GRABBED``
+      - 0x0002
+      - This control is temporarily unchangeable, for example because
+	another application took over control of the respective resource.
+	Such controls may be displayed specially in a user interface.
+	Attempts to change the control may result in an ``EBUSY`` error code.
+    * - ``V4L2_CTRL_FLAG_READ_ONLY``
+      - 0x0004
+      - This control is permanently readable only. Any attempt to change
+	the control will result in an ``EINVAL`` error code.
+    * - ``V4L2_CTRL_FLAG_UPDATE``
+      - 0x0008
+      - A hint that changing this control may affect the value of other
+	controls within the same control class. Applications should update
+	their user interface accordingly.
+    * - ``V4L2_CTRL_FLAG_INACTIVE``
+      - 0x0010
+      - This control is not applicable to the current configuration and
+	should be displayed accordingly in a user interface. For example
+	the flag may be set on a MPEG audio level 2 bitrate control when
+	MPEG audio encoding level 1 was selected with another control.
+    * - ``V4L2_CTRL_FLAG_SLIDER``
+      - 0x0020
+      - A hint that this control is best represented as a slider-like
+	element in a user interface.
+    * - ``V4L2_CTRL_FLAG_WRITE_ONLY``
+      - 0x0040
+      - This control is permanently writable only. Any attempt to read the
+	control will result in an ``EACCES`` error code error code. This flag
+	is typically present for relative controls or action controls
+	where writing a value will cause the device to carry out a given
+	action (e. g. motor control) but no meaningful value can be
+	returned.
+    * - ``V4L2_CTRL_FLAG_VOLATILE``
+      - 0x0080
+      - This control is volatile, which means that the value of the
+	control changes continuously. A typical example would be the
+	current gain value if the device is in auto-gain mode. In such a
+	case the hardware calculates the gain value based on the lighting
+	conditions which can change over time.
+
+	.. note::
+
+	   Setting a new value for a volatile control will be ignored
+	   unless
+	   :ref:`V4L2_CTRL_FLAG_EXECUTE_ON_WRITE <FLAG_EXECUTE_ON_WRITE>`
+	   is also set.
+	   Setting a new value for a volatile control will *never* trigger a
+	   :ref:`V4L2_EVENT_CTRL_CH_VALUE <ctrl-changes-flags>` event.
+    * - ``V4L2_CTRL_FLAG_HAS_PAYLOAD``
+      - 0x0100
+      - This control has a pointer type, so its value has to be accessed
+	using one of the pointer fields of struct
+	:c:type:`v4l2_ext_control`. This flag is set
+	for controls that are an array, string, or have a compound type.
+	In all cases you have to set a pointer to memory containing the
+	payload of the control.
+    * .. _FLAG_EXECUTE_ON_WRITE:
+
+      - ``V4L2_CTRL_FLAG_EXECUTE_ON_WRITE``
+      - 0x0200
+      - The value provided to the control will be propagated to the driver
+	even if it remains constant. This is required when the control
+	represents an action on the hardware. For example: clearing an
+	error flag or triggering the flash. All the controls of the type
+	``V4L2_CTRL_TYPE_BUTTON`` have this flag set.
+    * .. _FLAG_MODIFY_LAYOUT:
+
+      - ``V4L2_CTRL_FLAG_MODIFY_LAYOUT``
+      - 0x0400
+      - Changing this control value may modify the layout of the
+        buffer (for video devices) or the media bus format (for sub-devices).
+
+	A typical example would be the ``V4L2_CID_ROTATE`` control.
+
+	Note that typically controls with this flag will also set the
+	``V4L2_CTRL_FLAG_GRABBED`` flag when buffers are allocated or
+	streaming is in progress since most drivers do not support changing
+	the format in that case.
+
+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.
+
+EINVAL
+    The struct :ref:`v4l2_queryctrl <v4l2-queryctrl>` ``id`` is
+    invalid. The struct :ref:`v4l2_querymenu <v4l2-querymenu>` ``id``
+    is invalid or ``index`` is out of range (less than ``minimum`` or
+    greater than ``maximum``) or this particular menu item is not
+    supported by the driver.
+
+EACCES
+    An attempt was made to read a write-only control.
+
+.. [#f1]
+   ``V4L2_CTRL_FLAG_DISABLED`` was intended for two purposes: Drivers
+   can skip predefined controls not supported by the hardware (although
+   returning ``EINVAL`` would do as well), or disable predefined and private
+   controls after hardware detection without the trouble of reordering
+   control arrays and indices (``EINVAL`` cannot be used to skip private
+   controls because it would prematurely end the enumeration).