doc_rst: rename the media Sphinx suff to Documentation/media

The name of the subsystem is "media", and not "linux_tv". Also,
as we plan to add other stuff there in the future, let's
rename also the media uAPI book to media_uapi, to make it
clearer.

No functional changes.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 488 insertions, 0 deletions

diff --git a/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst b/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst
new file mode 100644
index 0000000000000..96b6eaca755c2
--- /dev/null
+++ b/Documentation/media/uapi/v4l/vidioc-g-ext-ctrls.rst
@@ -0,0 +1,488 @@
+.. -*- coding: utf-8; mode: rst -*-
+
+.. _VIDIOC_G_EXT_CTRLS:
+
+******************************************************************
+ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS
+******************************************************************
+
+Name
+====
+
+VIDIOC_G_EXT_CTRLS - VIDIOC_S_EXT_CTRLS - VIDIOC_TRY_EXT_CTRLS - Get or set the value of several controls, try control values
+
+
+Synopsis
+========
+
+.. cpp:function:: int ioctl( int fd, int request, struct v4l2_ext_controls *argp )
+
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :ref:`open() <func-open>`.
+
+``request``
+    VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS,
+    VIDIOC_TRY_EXT_CTRLS
+
+``argp``
+
+
+Description
+===========
+
+These ioctls allow the caller to get or set multiple controls
+atomically. Control IDs are grouped into control classes (see
+:ref:`ctrl-class`) and all controls in the control array must belong
+to the same control class.
+
+Applications must always fill in the ``count``, ``which``, ``controls``
+and ``reserved`` fields of struct
+:ref:`v4l2_ext_controls <v4l2-ext-controls>`, and initialize the
+struct :ref:`v4l2_ext_control <v4l2-ext-control>` array pointed to
+by the ``controls`` fields.
+
+To get the current value of a set of controls applications initialize
+the ``id``, ``size`` and ``reserved2`` fields of each struct
+:ref:`v4l2_ext_control <v4l2-ext-control>` and call the
+:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctl. String controls controls must also set the
+``string`` field. Controls of compound types
+(``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is set) must set the ``ptr`` field.
+
+If the ``size`` is too small to receive the control result (only
+relevant for pointer-type controls like strings), then the driver will
+set ``size`` to a valid value and return an ``ENOSPC`` error code. You
+should re-allocate the memory to this new size and try again. For the
+string type it is possible that the same issue occurs again if the
+string has grown in the meantime. It is recommended to call
+:ref:`VIDIOC_QUERYCTRL` first and use
+``maximum``\ +1 as the new ``size`` value. It is guaranteed that that is
+sufficient memory.
+
+N-dimensional arrays are set and retrieved row-by-row. You cannot set a
+partial array, all elements have to be set or retrieved. The total size
+is calculated as ``elems`` * ``elem_size``. These values can be obtained
+by calling :ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>`.
+
+To change the value of a set of controls applications initialize the
+``id``, ``size``, ``reserved2`` and ``value/value64/string/ptr`` fields
+of each struct :ref:`v4l2_ext_control <v4l2-ext-control>` and call
+the :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctl. The controls will only be set if *all*
+control values are valid.
+
+To check if a set of controls have correct values applications
+initialize the ``id``, ``size``, ``reserved2`` and
+``value/value64/string/ptr`` fields of each struct
+:ref:`v4l2_ext_control <v4l2-ext-control>` and call the
+:ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctl. It is up to the driver whether wrong
+values are automatically adjusted to a valid value or if an error is
+returned.
+
+When the ``id`` or ``which`` is invalid drivers return an ``EINVAL`` error
+code. When the value is out of bounds drivers can choose to take the
+closest valid value or return an ``ERANGE`` error code, whatever seems more
+appropriate. In the first case the new value is set in struct
+:ref:`v4l2_ext_control <v4l2-ext-control>`. If the new control value
+is inappropriate (e.g. the given menu index is not supported by the menu
+control), then this will also result in an ``EINVAL`` error code error.
+
+The driver will only set/get these controls if all control values are
+correct. This prevents the situation where only some of the controls
+were set/get. Only low-level errors (e. g. a failed i2c command) can
+still cause this situation.
+
+
+.. _v4l2-ext-control:
+
+.. flat-table:: struct v4l2_ext_control
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 1 2
+
+
+    -  .. row 1
+
+       -  __u32
+
+       -  ``id``
+
+       -
+       -  Identifies the control, set by the application.
+
+    -  .. row 2
+
+       -  __u32
+
+       -  ``size``
+
+       -
+       -  The total size in bytes of the payload of this control. This is
+	  normally 0, but for pointer controls this should be set to the
+	  size of the memory containing the payload, or that will receive
+	  the payload. If :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` finds that this value is
+	  less than is required to store the payload result, then it is set
+	  to a value large enough to store the payload result and ``ENOSPC`` is
+	  returned. Note that for string controls this ``size`` field should
+	  not be confused with the length of the string. This field refers
+	  to the size of the memory that contains the string. The actual
+	  *length* of the string may well be much smaller.
+
+    -  .. row 3
+
+       -  __u32
+
+       -  ``reserved2``\ [1]
+
+       -
+       -  Reserved for future extensions. Drivers and applications must set
+	  the array to zero.
+
+    -  .. row 4
+
+       -  union
+
+       -  (anonymous)
+
+    -  .. row 5
+
+       -
+       -  __s32
+
+       -  ``value``
+
+       -  New value or current value. Valid if this control is not of type
+	  ``V4L2_CTRL_TYPE_INTEGER64`` and ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is
+	  not set.
+
+    -  .. row 6
+
+       -
+       -  __s64
+
+       -  ``value64``
+
+       -  New value or current value. Valid if this control is of type
+	  ``V4L2_CTRL_TYPE_INTEGER64`` and ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is
+	  not set.
+
+    -  .. row 7
+
+       -
+       -  char *
+
+       -  ``string``
+
+       -  A pointer to a string. Valid if this control is of type
+	  ``V4L2_CTRL_TYPE_STRING``.
+
+    -  .. row 8
+
+       -
+       -  __u8 *
+
+       -  ``p_u8``
+
+       -  A pointer to a matrix control of unsigned 8-bit values. Valid if
+	  this control is of type ``V4L2_CTRL_TYPE_U8``.
+
+    -  .. row 9
+
+       -
+       -  __u16 *
+
+       -  ``p_u16``
+
+       -  A pointer to a matrix control of unsigned 16-bit values. Valid if
+	  this control is of type ``V4L2_CTRL_TYPE_U16``.
+
+    -  .. row 10
+
+       -
+       -  __u32 *
+
+       -  ``p_u32``
+
+       -  A pointer to a matrix control of unsigned 32-bit values. Valid if
+	  this control is of type ``V4L2_CTRL_TYPE_U32``.
+
+    -  .. row 11
+
+       -
+       -  void *
+
+       -  ``ptr``
+
+       -  A pointer to a compound type which can be an N-dimensional array
+	  and/or a compound type (the control's type is >=
+	  ``V4L2_CTRL_COMPOUND_TYPES``). Valid if
+	  ``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is set for this control.
+
+
+
+.. _v4l2-ext-controls:
+
+.. flat-table:: struct v4l2_ext_controls
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2 1
+
+
+    -  .. row 1
+
+       -  union
+
+       -  (anonymous)
+
+    -  .. row 2
+
+       -
+       -  __u32
+
+       -  ``ctrl_class``
+
+       -  The control class to which all controls belong, see
+	  :ref:`ctrl-class`. Drivers that use a kernel framework for
+	  handling controls will also accept a value of 0 here, meaning that
+	  the controls can belong to any control class. Whether drivers
+	  support this can be tested by setting ``ctrl_class`` to 0 and
+	  calling :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` with a ``count`` of 0. If that
+	  succeeds, then the driver supports this feature.
+
+    -  .. row 3
+
+       -
+       -  __u32
+
+       -  ``which``
+
+       -  Which value of the control to get/set/try.
+	  ``V4L2_CTRL_WHICH_CUR_VAL`` will return the current value of the
+	  control and ``V4L2_CTRL_WHICH_DEF_VAL`` will return the default
+	  value of the control. Please note that you can only get the
+	  default value of the control, you cannot set or try it.
+
+	  For backwards compatibility you can also use a control class here
+	  (see :ref:`ctrl-class`). In that case all controls have to
+	  belong to that control class. This usage is deprecated, instead
+	  just use ``V4L2_CTRL_WHICH_CUR_VAL``. There are some very old
+	  drivers that do not yet support ``V4L2_CTRL_WHICH_CUR_VAL`` and
+	  that require a control class here. You can test for such drivers
+	  by setting ctrl_class to ``V4L2_CTRL_WHICH_CUR_VAL`` and calling
+	  VIDIOC_TRY_EXT_CTRLS with a count of 0. If that fails, then the
+	  driver does not support ``V4L2_CTRL_WHICH_CUR_VAL``.
+
+    -  .. row 4
+
+       -  __u32
+
+       -  ``count``
+
+       -  The number of controls in the controls array. May also be zero.
+
+    -  .. row 5
+
+       -  __u32
+
+       -  ``error_idx``
+
+       -  Set by the driver in case of an error. If the error is associated
+	  with a particular control, then ``error_idx`` is set to the index
+	  of that control. If the error is not related to a specific
+	  control, or the validation step failed (see below), then
+	  ``error_idx`` is set to ``count``. The value is undefined if the
+	  ioctl returned 0 (success).
+
+	  Before controls are read from/written to hardware a validation
+	  step takes place: this checks if all controls in the list are
+	  valid controls, if no attempt is made to write to a read-only
+	  control or read from a write-only control, and any other up-front
+	  checks that can be done without accessing the hardware. The exact
+	  validations done during this step are driver dependent since some
+	  checks might require hardware access for some devices, thus making
+	  it impossible to do those checks up-front. However, drivers should
+	  make a best-effort to do as many up-front checks as possible.
+
+	  This check is done to avoid leaving the hardware in an
+	  inconsistent state due to easy-to-avoid problems. But it leads to
+	  another problem: the application needs to know whether an error
+	  came from the validation step (meaning that the hardware was not
+	  touched) or from an error during the actual reading from/writing
+	  to hardware.
+
+	  The, in hindsight quite poor, solution for that is to set
+	  ``error_idx`` to ``count`` if the validation failed. This has the
+	  unfortunate side-effect that it is not possible to see which
+	  control failed the validation. If the validation was successful
+	  and the error happened while accessing the hardware, then
+	  ``error_idx`` is less than ``count`` and only the controls up to
+	  ``error_idx-1`` were read or written correctly, and the state of
+	  the remaining controls is undefined.
+
+	  Since :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` does not access hardware there is
+	  also no need to handle the validation step in this special way, so
+	  ``error_idx`` will just be set to the control that failed the
+	  validation step instead of to ``count``. This means that if
+	  :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` fails with ``error_idx`` set to ``count``,
+	  then you can call :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` to try to discover the
+	  actual control that failed the validation step. Unfortunately,
+	  there is no ``TRY`` equivalent for :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`.
+
+    -  .. row 6
+
+       -  __u32
+
+       -  ``reserved``\ [2]
+
+       -  Reserved for future extensions. Drivers and applications must set
+	  the array to zero.
+
+    -  .. row 7
+
+       -  struct :ref:`v4l2_ext_control <v4l2-ext-control>` *
+
+       -  ``controls``
+
+       -  Pointer to an array of ``count`` v4l2_ext_control structures.
+	  Ignored if ``count`` equals zero.
+
+
+
+.. _ctrl-class:
+
+.. flat-table:: Control classes
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       3 1 4
+
+
+    -  .. row 1
+
+       -  ``V4L2_CTRL_CLASS_USER``
+
+       -  0x980000
+
+       -  The class containing user controls. These controls are described
+	  in :ref:`control`. All controls that can be set using the
+	  :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` and
+	  :ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` ioctl belong to this
+	  class.
+
+    -  .. row 2
+
+       -  ``V4L2_CTRL_CLASS_MPEG``
+
+       -  0x990000
+
+       -  The class containing MPEG compression controls. These controls are
+	  described in :ref:`mpeg-controls`.
+
+    -  .. row 3
+
+       -  ``V4L2_CTRL_CLASS_CAMERA``
+
+       -  0x9a0000
+
+       -  The class containing camera controls. These controls are described
+	  in :ref:`camera-controls`.
+
+    -  .. row 4
+
+       -  ``V4L2_CTRL_CLASS_FM_TX``
+
+       -  0x9b0000
+
+       -  The class containing FM Transmitter (FM TX) controls. These
+	  controls are described in :ref:`fm-tx-controls`.
+
+    -  .. row 5
+
+       -  ``V4L2_CTRL_CLASS_FLASH``
+
+       -  0x9c0000
+
+       -  The class containing flash device controls. These controls are
+	  described in :ref:`flash-controls`.
+
+    -  .. row 6
+
+       -  ``V4L2_CTRL_CLASS_JPEG``
+
+       -  0x9d0000
+
+       -  The class containing JPEG compression controls. These controls are
+	  described in :ref:`jpeg-controls`.
+
+    -  .. row 7
+
+       -  ``V4L2_CTRL_CLASS_IMAGE_SOURCE``
+
+       -  0x9e0000
+
+       -  The class containing image source controls. These controls are
+	  described in :ref:`image-source-controls`.
+
+    -  .. row 8
+
+       -  ``V4L2_CTRL_CLASS_IMAGE_PROC``
+
+       -  0x9f0000
+
+       -  The class containing image processing controls. These controls are
+	  described in :ref:`image-process-controls`.
+
+    -  .. row 9
+
+       -  ``V4L2_CTRL_CLASS_FM_RX``
+
+       -  0xa10000
+
+       -  The class containing FM Receiver (FM RX) controls. These controls
+	  are described in :ref:`fm-rx-controls`.
+
+    -  .. row 10
+
+       -  ``V4L2_CTRL_CLASS_RF_TUNER``
+
+       -  0xa20000
+
+       -  The class containing RF tuner controls. These controls are
+	  described in :ref:`rf-tuner-controls`.
+
+
+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_ext_control <v4l2-ext-control>` ``id`` is
+    invalid, the struct :ref:`v4l2_ext_controls <v4l2-ext-controls>`
+    ``which`` is invalid, or the struct
+    :ref:`v4l2_ext_control <v4l2-ext-control>` ``value`` was
+    inappropriate (e.g. the given menu index is not supported by the
+    driver). This error code is also returned by the
+    :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctls if two or
+    more control values are in conflict.
+
+ERANGE
+    The struct :ref:`v4l2_ext_control <v4l2-ext-control>` ``value``
+    is out of bounds.
+
+EBUSY
+    The control is temporarily not changeable, possibly because another
+    applications took over control of the device function this control
+    belongs to.
+
+ENOSPC
+    The space reserved for the control's payload is insufficient. The
+    field ``size`` is set to a value that is enough to store the payload
+    and this error code is returned.
+
+EACCES
+    Attempt to try or set a read-only control or to get a write-only
+    control.