Re: [PATCH v1 2/3] v4l: Add AUTO option for the V4L2_CID_POWER_LINE_FREQUENCY control

[Sakari Ailus <sakari.ailus@xxxxxx>]

Hi Sylwester,

On Tue, Sep 20, 2011 at 01:58:58PM +0200, Sylwester Nawrocki wrote:
> V4L2_CID_POWER_LINE_FREQUENCY control allows applications to instruct
> a driver what is the power line frequency so an appropriate filter
> can be used by the device to cancel flicker by compensating the light
> intensity ripple and thus. Currently in the menu we have entries for
> 50 and 60 Hz and for entirely disabling the anti-flicker filter.
> However some devices are capable of automatically detecting the
> frequency, so add V4L2_CID_POWER_LINE_FREQUENCY_AUTO entry for them.
> 
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
>  Documentation/DocBook/media/v4l/controls.xml |    5 +++--
>  drivers/media/video/v4l2-ctrls.c             |    1 +
>  include/linux/videodev2.h                    |    1 +
>  3 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
> index 2420e4a..c6b3c46 100644
> --- a/Documentation/DocBook/media/v4l/controls.xml
> +++ b/Documentation/DocBook/media/v4l/controls.xml
> @@ -232,8 +232,9 @@ control is deprecated. New drivers and applications should use the
>  	    <entry>Enables a power line frequency filter to avoid
>  flicker. Possible values for <constant>enum v4l2_power_line_frequency</constant> are:
>  <constant>V4L2_CID_POWER_LINE_FREQUENCY_DISABLED</constant> (0),
> -<constant>V4L2_CID_POWER_LINE_FREQUENCY_50HZ</constant> (1) and
> -<constant>V4L2_CID_POWER_LINE_FREQUENCY_60HZ</constant> (2).</entry>
> +<constant>V4L2_CID_POWER_LINE_FREQUENCY_50HZ</constant> (1),
> +<constant>V4L2_CID_POWER_LINE_FREQUENCY_60HZ</constant> (2) and
> +<constant>V4L2_CID_POWER_LINE_FREQUENCY_AUTO</constant> (3).</entry>

A stupid question: wouldn't this be a case for a new control for automatic
power line frequency, in other words enabling or disabling it?

>  	  </row>
>  	  <row>
>  	    <entry><constant>V4L2_CID_HUE_AUTO</constant></entry>
> diff --git a/drivers/media/video/v4l2-ctrls.c b/drivers/media/video/v4l2-ctrls.c
> index 06b6014..20abe5d 100644
> --- a/drivers/media/video/v4l2-ctrls.c
> +++ b/drivers/media/video/v4l2-ctrls.c
> @@ -210,6 +210,7 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
>  		"Disabled",
>  		"50 Hz",
>  		"60 Hz",
> +		"Auto",
>  		NULL
>  	};
>  	static const char * const camera_exposure_auto[] = {
> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> index c33f462..87210f1 100644
> --- a/include/linux/videodev2.h
> +++ b/include/linux/videodev2.h
> @@ -1125,6 +1125,7 @@ enum v4l2_power_line_frequency {
>  	V4L2_CID_POWER_LINE_FREQUENCY_DISABLED	= 0,
>  	V4L2_CID_POWER_LINE_FREQUENCY_50HZ	= 1,
>  	V4L2_CID_POWER_LINE_FREQUENCY_60HZ	= 2,
> +	V4L2_CID_POWER_LINE_FREQUENCY_AUTO	= 3,
>  };
>  #define V4L2_CID_HUE_AUTO			(V4L2_CID_BASE+25)
>  #define V4L2_CID_WHITE_BALANCE_TEMPERATURE	(V4L2_CID_BASE+26)
> -- 
> 1.7.6.3
> 

-- 
Sakari Ailus
e-mail: sakari.ailus@xxxxxx	jabber/XMPP/Gmail: sailus@xxxxxxxxxxxxxx
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