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diff --git a/Documentation/media/uapi/v4l/vidioc-queryctrl.rst b/Documentation/media/uapi/v4l/vidioc-queryctrl.rst deleted file mode 100644 index 8971f4cfb16e..000000000000 --- a/Documentation/media/uapi/v4l/vidioc-queryctrl.rst +++ /dev/null @@ -1,616 +0,0 @@ -.. 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/media/uapi/fdl-appendix.rst. -.. -.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections - -.. _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 -======== - -.. c:function:: int ioctl( int fd, int VIDIOC_QUERYCTRL, struct v4l2_queryctrl *argp ) - :name: VIDIOC_QUERYCTRL - -.. c:function:: int ioctl( int fd, VIDIOC_QUERY_EXT_CTRL, struct v4l2_query_ext_ctrl *argp ) - :name: VIDIOC_QUERY_EXT_CTRL - -.. c:function:: int ioctl( int fd, VIDIOC_QUERYMENU, struct v4l2_querymenu *argp ) - :name: VIDIOC_QUERYMENU - - -Arguments -========= - -``fd`` - File descriptor returned by :ref:`open() <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). |