Re: [PATCH] media: v4l2-ctrl: add a helper fucntion to modify themenu

[Manjunath Hadli]

Hi Hans,

Thanks for the review.

On Monday 10 September 2012 05:43 PM, Hans Verkuil wrote:
> On Mon September 10 2012 13:57:36 Prabhakar Lad wrote:
>> From: Lad, Prabhakar <prabhakar.lad@xxxxxx>
>>
>> Signed-off-by: Lad, Prabhakar <prabhakar.lad@xxxxxx>
>> Signed-off-by: Manjunath Hadli <manjunath.hadli@xxxxxx>
>> Cc: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>> Cc: Sakari Ailus <sakari.ailus@xxxxxx>
>> Cc: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
>> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>> Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxx>
>> Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
>> Cc: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
>> Cc: Rob Landley <rob@xxxxxxxxxxx>
>> ---
>>  Documentation/video4linux/v4l2-controls.txt |   26 +++++++++++++++++++++++++
>>  drivers/media/v4l2-core/v4l2-ctrls.c        |   28 +++++++++++++++++++++++++++
>>  include/media/v4l2-ctrls.h                  |   14 +++++++++++++
>>  3 files changed, 68 insertions(+), 0 deletions(-)
>>
>> diff --git a/Documentation/video4linux/v4l2-controls.txt b/Documentation/video4linux/v4l2-controls.txt
>> index 43da22b..54a9539 100644
>> --- a/Documentation/video4linux/v4l2-controls.txt
>> +++ b/Documentation/video4linux/v4l2-controls.txt
>> @@ -196,6 +196,32 @@ the error code at the end. Saves a lot of repetitive error checking.
>>  It is recommended to add controls in ascending control ID order: it will be
>>  a bit faster that way.
>>  
>> +2.1) Changing the menu of a standard control:
>> +There are suitations when the control is standard but the menu items may be
>> +device specific, in such cases the framework provides the helper to do that.
> 
> The "Menu Controls" section in this file would be a better place to add this.
> 
Ok.

>> +
>> +struct v4l2_ctrl * v4l2_ctrl_modify_menu(struct v4l2_ctrl *ctrl,
>> +	const char * const *qmenu, s32 min, s32 max,
>> +	u32 menu_skip_mask, s32 def);
>> +
>> +This helper, function is used to modify the menu, min, max, mask and
>> +the default value to set.
>> +Example for usage:
>> +	static const char * const test_pattern[] = {
>> +		"Disabled",
>> +		"Vertical Bars",
>> +		"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, 0, 5, 0x3, 0);
>> +
>>  3) Optionally force initial control setup:
>>  
>>  	v4l2_ctrl_handler_setup(&foo->ctrl_handler);
>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
>> index d731422..ac0fb28 100644
>> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
>> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
>> @@ -2666,3 +2666,31 @@ unsigned int v4l2_ctrl_poll(struct file *file, struct poll_table_struct *wait)
>>  	return 0;
>>  }
>>  EXPORT_SYMBOL(v4l2_ctrl_poll);
>> +
>> +/* Helper function for standard menu controls to modify the menu */
>> +struct v4l2_ctrl *v4l2_ctrl_modify_menu(struct v4l2_ctrl *ctrl,
>> +					 const char * const *qmenu, s32 min,
> 
> The minimum is always 0 for menu controls, so this argument should be
> removed. It's not part of v4l2_ctrl_new_std_menu either.
> 
> There is no need to return the pointer here, so just set the return to void.
> 
Ok.

>> +					 s32 max, u32 menu_skip_mask, s32 def)
>> +{
>> +	if (ctrl->type != V4L2_CTRL_TYPE_MENU)
>> +		return NULL;
>> +
>> +	if (qmenu == NULL)
>> +		return NULL;
> 
> Change this to:
> 
> 	if (WARN_ON(ctrl->type != V4L2_CTRL_TYPE_MENU || qmenu == NULL))
> 		return;
> 
Ok.

>> +
>> +	/* Determine if it is standard menu control */
>> +	if (!v4l2_ctrl_get_menu(ctrl->id))
>> +		return NULL;
> 
> This test can be removed. Why should we prohibit calling this function for
> non-standard controls?
> 
Any how how if its custom control, the menu will be provided by user
itself, so why would he fell the necessity of this function ? But
providing an option wont harm I'll remove it.

>> +
>> +	if ((def > max) || (max < min))
>> +		return NULL;
> 
> Also replace with if (WARN_ON(def < 0 || def > max)).
> 
> All these errors are driver errors and so should just report it in the kernel
> log and then bail out.
>
Ok.

>> +
>> +	ctrl->qmenu = qmenu;
>> +	ctrl->minimum = min;
> 
> No need to set minimum. It's already 0.
> 
Ok.

Regards,
--Prabhakar Lad

>> +	ctrl->maximum = max;
>> +	ctrl->menu_skip_mask = menu_skip_mask;
>> +	ctrl->cur.val = ctrl->val = ctrl->default_value = def;
>> +
>> +	return ctrl;
>> +}
>> +EXPORT_SYMBOL(v4l2_ctrl_modify_menu);
>> diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
>> index 776605f..5b0ea04 100644
>> --- a/include/media/v4l2-ctrls.h
>> +++ b/include/media/v4l2-ctrls.h
>> @@ -488,6 +488,20 @@ static inline void v4l2_ctrl_unlock(struct v4l2_ctrl *ctrl)
>>  	mutex_unlock(ctrl->handler->lock);
>>  }
>>  
>> +/**
>> + * v4l2_ctrl_modify_menu() - Modify the menu. This function is used when the
>> + * control is standard but the menu is specific to device.
>> + * @ctrl:		The control to change the menu.
>> + * @qmenu:		The menu to which control will point to.
>> + * @min:		Minimum value of the control.
>> + * @max:		Maximum valur of the control.
>> + * @menu_skip_mask:	The control's skip mask for menu controls.
>> + * @def:		The default value for control.
>> + */
>> +struct v4l2_ctrl *v4l2_ctrl_modify_menu(struct v4l2_ctrl *ctrl,
>> +					 const char * const *qmenu, s32 min,
>> +					 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.
>>    *
>>
> 
> Regards,
> 
> 	Hans
> 

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