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

[Prabhakar Lad <prabhakar.lad@ti.com>]

On Monday 10 September 2012 06:06 PM, Manjunath Hadli wrote:
> 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@ti.com>
>>>
>>> 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: Rob Landley <rob@landley.net>
>>> ---
>>>  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
> 
My Bad :(. Replied with Manju's ID.

Thanks,
--Prabhakar

>>> +	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
>>
>