On 02/17/2015 03:41 PM, Ricardo Ribalda Delgado wrote:
> Volatile variables are also writable now. Update the documentation
> accordingly.
>
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.riba...@gmail.com>
> ---
> Documentation/DocBook/media/v4l/vidioc-dqevent.xml | 7 ++++---
> Documentation/DocBook/media/v4l/vidioc-queryctrl.xml | 6 ++++--
> Documentation/video4linux/v4l2-controls.txt | 4 +++-
> 3 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
> b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
> index b036f89..38d907e 100644
> --- a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
> +++ b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
> @@ -318,9 +318,10 @@
> <entry><constant>V4L2_EVENT_CTRL_CH_VALUE</constant></entry>
> <entry>0x0001</entry>
> <entry>This control event was triggered because the value of the
> control
> - changed. Special case: if a button control is pressed, then this
> - event is sent as well, even though there is not explicit value
> - associated with a button control.</entry>
> + changed. Special cases: Volatile controls do no generate this
> event;
Volatile -> volatile
no -> not
event; -> event.
> + If a button control is pressed, then this event is sent as well,
> + even though there is not explicit value associated with a button
Hmm: not -> no
:-)
> + control.</entry>
> </row>
> <row>
> <entry><constant>V4L2_EVENT_CTRL_CH_FLAGS</constant></entry>
> diff --git a/Documentation/DocBook/media/v4l/vidioc-queryctrl.xml
> b/Documentation/DocBook/media/v4l/vidioc-queryctrl.xml
> index 2bd98fd..6e1e98d 100644
> --- a/Documentation/DocBook/media/v4l/vidioc-queryctrl.xml
> +++ b/Documentation/DocBook/media/v4l/vidioc-queryctrl.xml
> @@ -599,8 +599,10 @@ writing a value will cause the device to carry out a
> given action
> <entry>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 that setting a new
> value for
> -a volatile control will have no effect. The new value will just be
> ignored.</entry>
> +the lighting conditions which can change over time. Another example would be
> an error
> +flag (missed trigger, invalid voltage on the sensor). In those situations
> the user
> +could write to the control to acknowledge the error, but that write will
> never
> +generate a <constant>V4L2_EVENT_CTRL_CH_VALUE</constant> event.<entry>
> </row>
> <row>
> <entry><constant>V4L2_CTRL_FLAG_HAS_PAYLOAD</constant></entry>
> diff --git a/Documentation/video4linux/v4l2-controls.txt
> b/Documentation/video4linux/v4l2-controls.txt
> index 0f84ce8..5517db6 100644
> --- a/Documentation/video4linux/v4l2-controls.txt
> +++ b/Documentation/video4linux/v4l2-controls.txt
> @@ -344,7 +344,9 @@ implement g_volatile_ctrl like this:
> }
>
> Note that you use the 'new value' union as well in g_volatile_ctrl. In
> general
> -controls that need to implement g_volatile_ctrl are read-only controls.
> +controls that need to implement g_volatile_ctrl are read-only controls. If
> they
> +are not, a V4L2_EVENT_CTRL_CH_VALUE will not be generated when the control
> +changes.
>
> To mark a control as volatile you have to set V4L2_CTRL_FLAG_VOLATILE:
>
>
With those typo fixes:
Acked-by: Hans Verkuil <hans.verk...@cisco.com>
Thanks!
Hans
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