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media: docs: v4l2-controls: rearrange control initialization sequence 

The code snippet showing how to add controls to the driver’s top-level
struct is present twice, but only the second time it is split in the V4L2
and subdev cases. Consolidate everything at the beginning.

Also remove the "Where foo->bar is of type struct baz" sentences, this
obvious from the code.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Luca Ceresoli 2019-06-13 10:18:22 -04:00 committed by Mauro Carvalho Chehab
parent 9e75efb0f2
commit e36160b842
1 changed files with 17 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
Documentation/media/kapi/v4l2-controls.rst
View File

@ -52,15 +52,29 @@ Basic usage for V4L2 and sub-device drivers
1.1) Add the handler to your driver's top-level struct:
For V4L2 drivers:
.. code-block:: none
struct foo_dev {
...
struct v4l2_device v4l2_dev;
...
struct v4l2_ctrl_handler ctrl_handler;
...
};
struct foo_dev *foo;
For sub-device drivers:
.. code-block:: none
struct foo_dev {
...
struct v4l2_subdev sd;
...
struct v4l2_ctrl_handler ctrl_handler;
...
};
1.2) Initialize the handler:
@ -74,43 +88,23 @@ information. It is a hint only.
1.3) Hook the control handler into the driver:
1.3.1) For V4L2 drivers do this:
For V4L2 drivers:
.. code-block:: none
struct foo_dev {
...
struct v4l2_device v4l2_dev;
...
struct v4l2_ctrl_handler ctrl_handler;
...
};
foo->v4l2_dev.ctrl_handler = &foo->ctrl_handler;
Where foo->v4l2_dev is of type struct v4l2_device.
Finally, remove all control functions from your v4l2_ioctl_ops (if any):
vidioc_queryctrl, vidioc_query_ext_ctrl, vidioc_querymenu, vidioc_g_ctrl,
vidioc_s_ctrl, vidioc_g_ext_ctrls, vidioc_try_ext_ctrls and vidioc_s_ext_ctrls.
Those are now no longer needed.
1.3.2) For sub-device drivers do this:
For sub-device drivers:
.. code-block:: none
struct foo_dev {
...
struct v4l2_subdev sd;
...
struct v4l2_ctrl_handler ctrl_handler;
...
};
foo->sd.ctrl_handler = &foo->ctrl_handler;
Where foo->sd is of type struct v4l2_subdev.
1.4) Clean up the handler at the end:
.. code-block:: none