@@ -138,11 +138,12 @@ still cause this situation.
- Identifies the control, set by the application.
* - __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
+ - The total size in bytes of the payload of this control.
+ * - :cspan:`2` The ``size`` field is normally 0, but for pointer
+ controls this should be set to the size of the memory that contains
+ 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.
@@ -242,30 +243,19 @@ still cause this situation.
* - union {
- (anonymous)
- * - __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.
* - __u32
- ``which``
- Which value of the control to get/set/try.
- ``V4L2_CTRL_WHICH_CUR_VAL`` will return the current value of the
- control, ``V4L2_CTRL_WHICH_DEF_VAL`` will return the default
+ * - :cspan:`2` ``V4L2_CTRL_WHICH_CUR_VAL`` will return the current value of
+ the control, ``V4L2_CTRL_WHICH_DEF_VAL`` will return the default
value of the control and ``V4L2_CTRL_WHICH_REQUEST_VAL`` indicates that
these controls have to be retrieved from a request or tried/set for
a request. In the latter case the ``request_fd`` field contains the
file descriptor of the request that should be used. If the device
does not support requests, then ``EACCES`` will be returned.
- .. note::
-
- When using ``V4L2_CTRL_WHICH_DEF_VAL`` be aware that you can only
- get the default value of the control, you cannot set or try it.
+ When using ``V4L2_CTRL_WHICH_DEF_VAL`` be aware 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
@@ -273,9 +263,12 @@ still cause this situation.
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``.
+ by setting ``which`` to ``V4L2_CTRL_WHICH_CUR_VAL`` and calling
+ :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` with a count of 0.
+ If that fails, then the driver does not support ``V4L2_CTRL_WHICH_CUR_VAL``.
+ * - __u32
+ - ``ctrl_class``
+ - Deprecated name kept for backwards compatibility. Use ``which`` instead.
* - }
-
* - __u32
@@ -283,7 +276,8 @@ still cause this situation.
- The number of controls in the controls array. May also be zero.
* - __u32
- ``error_idx``
- - Set by the driver in case of an error. If the error is associated
+ - Index of the failing control. Set by the driver in case of an error.
+ * - :cspan:`2` 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
The VIDIOC_G/S/TRY_EXT_CTRLS documentation has large explanatory texts for some of the fields in a table. This makes it hard to read. Move those text to a new cell spanning the whole width of the table, similar to what was done for struct v4l2_pix_format. This makes it much more readable. Also move the 'ctrl_class' description to below the 'which' description and just mention that it is deprecated and that 'which' should be used instead. Finally remove 'note::' for the V4L2_CTRL_WHICH_DEF_VAL description. It doesn't have to be marked as a note, it's just a simple paragraph. Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> ---