Re: [PATCH v3] media: v4l2-ctrl: add a helper function to modify the menu

[Hans Verkuil <hverkuil@xs4all.nl>]

On Tue 11 September 2012 16:23:38 Prabhakar Lad wrote:
> From: Lad, Prabhakar <prabhakar.lad@ti.com>
> 
> Add a helper function to modify the menu, max and default value
> to set.
> 
> Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>
> Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
> Cc: Hans Verkuil <hans.verkuil@cisco.com>
> Cc: Sakari Ailus <sakari.ailus@iki.fi>
> Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> Cc: Rob Landley <rob@landley.net>

Thanks!

Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>

Regards,

	Hans

> ---
> Changes for v3:
> 1: Fixed style/grammer issues as pointed by Hans.
>    Thanks Hans for providing the description.
> 
> Changes for v2:
> 1: Fixed review comments from Hans, to have return type as
>    void, add WARN_ON() for fail conditions, allow this fucntion
>    to modify the menu of custom controls.
> 
>  Documentation/video4linux/v4l2-controls.txt |   29 +++++++++++++++++++++++++++
>  drivers/media/v4l2-core/v4l2-ctrls.c        |   17 +++++++++++++++
>  include/media/v4l2-ctrls.h                  |   11 ++++++++++
>  3 files changed, 57 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/video4linux/v4l2-controls.txt b/Documentation/video4linux/v4l2-controls.txt
> index 43da22b..01d0a82 100644
> --- a/Documentation/video4linux/v4l2-controls.txt
> +++ b/Documentation/video4linux/v4l2-controls.txt
> @@ -367,6 +367,35 @@ it to 0 means that all menu items are supported.
>  You set this mask either through the v4l2_ctrl_config struct for a custom
>  control, or by calling v4l2_ctrl_new_std_menu().
>  
> +There are situations where menu items may be device specific. In such cases the
> +framework provides a helper function to change the menu:
> +
> +void v4l2_ctrl_modify_menu(struct v4l2_ctrl *ctrl, const char * const *qmenu,
> +	s32 max, u32 menu_skip_mask, s32 def);
> +
> +A good example is the test pattern control for capture/display/sensors devices
> +that have the capability to generate test patterns. These test patterns are
> +hardware specific, so the contents of the menu will vary from device to device.
> +
> +This helper function is used to modify the menu, max, mask and the default
> +value of the control.
> +
> +Example:
> +
> +	static const char * const test_pattern[] = {
> +		"Disabled",
> +		"Vertical Bars",
> +		"Solid Black",
> +		"Solid White",
> +		NULL,
> +	};
> +	struct v4l2_ctrl *test_pattern_ctrl =
> +		v4l2_ctrl_new_std_menu(&foo->ctrl_handler, &foo_ctrl_ops,
> +			V4L2_CID_TEST_PATTERN, V4L2_TEST_PATTERN_DISABLED, 0,
> +			V4L2_TEST_PATTERN_DISABLED);
> +
> +	v4l2_ctrl_modify_menu(test_pattern_ctrl, test_pattern, 3, 0,
> +		V4L2_TEST_PATTERN_DISABLED);
>  
>  Custom Controls
>  ===============
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> index d731422..d89b460 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -2666,3 +2666,20 @@ unsigned int v4l2_ctrl_poll(struct file *file, struct poll_table_struct *wait)
>  	return 0;
>  }
>  EXPORT_SYMBOL(v4l2_ctrl_poll);
> +
> +/* Helper function for modifying the menu */
> +void v4l2_ctrl_modify_menu(struct v4l2_ctrl *ctrl, const char * const *qmenu,
> +			   s32 max, u32 menu_skip_mask, s32 def)
> +{
> +	if (WARN_ON(ctrl->type != V4L2_CTRL_TYPE_MENU || qmenu == NULL))
> +		return;
> +
> +	if (WARN_ON(def < 0 || def > max))
> +		return;
> +
> +	ctrl->qmenu = qmenu;
> +	ctrl->maximum = max;
> +	ctrl->menu_skip_mask = menu_skip_mask;
> +	ctrl->cur.val = ctrl->val = ctrl->default_value = def;
> +}
> +EXPORT_SYMBOL(v4l2_ctrl_modify_menu);
> diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
> index 776605f..5303489 100644
> --- a/include/media/v4l2-ctrls.h
> +++ b/include/media/v4l2-ctrls.h
> @@ -488,6 +488,17 @@ static inline void v4l2_ctrl_unlock(struct v4l2_ctrl *ctrl)
>  	mutex_unlock(ctrl->handler->lock);
>  }
>  
> +/**
> + * v4l2_ctrl_modify_menu() - This function is used to modify the menu.
> + * @ctrl:		The control whose menu should be modified.
> + * @qmenu:		The new menu.
> + * @max:		Maximum value of the control.
> + * @menu_skip_mask:	The control's skip mask for menu controls.
> + * @def:		The default value for control to be set.
> + */
> +void v4l2_ctrl_modify_menu(struct v4l2_ctrl *ctrl, const char * const *qmenu,
> +			   s32 max, u32 menu_skip_mask, s32 def);
> +
>  /** v4l2_ctrl_g_ctrl() - Helper function to get the control's value from within a driver.
>    * @ctrl:	The control.
>    *
>