linux-kernel - Re: [PATCH] media: v4l2-ctrl: Add p_def to v4l2_ctrl

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Message-ID: <0e98973c-96a8-dc2e-295f-225ab3b1eae0@xs4all.nl>
Date:   Wed, 16 Oct 2019 14:32:04 +0200
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     Ricardo Ribalda Delgado <ribalda@...nel.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media <linux-media@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] media: v4l2-ctrl: Add p_def to v4l2_ctrl_config

On 10/16/19 2:20 PM, Ricardo Ribalda Delgado wrote:
> Hi Hans
> 
> Not that awkward, the user has to use the brand new
> v4l2_ctrl_ptr_create() ;). But if you prefer void * I can make the
> change.

Well, a struct v4l2_ctrl_config is typically a static const, so you can't use
v4l2_ctrl_ptr_create().

Hmm, perhaps it is as easy as:

static const struct v4l2_area def_area = {
	...
};

static const struct v4l2_ctrl_config ctrl = {
	...

	.p_def.p_area = &def_area,
	...
};

Can you do a quick compile check that I am not overlooking anything?

If this works, then I'll take this patch.

Regards,

	Hans

> 
> Regards
> 
> On Wed, Oct 16, 2019 at 2:17 PM Hans Verkuil <hverkuil-cisco@...all.nl> wrote:
>>
>> On 10/14/19 4:14 PM, Ricardo Ribalda Delgado wrote:
>>> This allows setting the default value on compound controls created via
>>> v4l2_ctrl_new_custom.
>>>
>>> Signed-off-by: Ricardo Ribalda Delgado <ribalda@...nel.org>
>>> ---
>>>  drivers/media/v4l2-core/v4l2-ctrls.c | 2 +-
>>>  include/media/v4l2-ctrls.h           | 2 ++
>>>  2 files changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
>>> index bf50d37ef6c1..12cf38f73f7b 100644
>>> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
>>> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
>>> @@ -2583,7 +2583,7 @@ struct v4l2_ctrl *v4l2_ctrl_new_custom(struct v4l2_ctrl_handler *hdl,
>>>                       type, min, max,
>>>                       is_menu ? cfg->menu_skip_mask : step, def,
>>>                       cfg->dims, cfg->elem_size,
>>> -                     flags, qmenu, qmenu_int, ptr_null, priv);
>>> +                     flags, qmenu, qmenu_int, cfg->p_def, priv);
>>>       if (ctrl)
>>>               ctrl->is_private = cfg->is_private;
>>>       return ctrl;
>>> diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
>>> index 26205ba3a0a0..2fca5b823961 100644
>>> --- a/include/media/v4l2-ctrls.h
>>> +++ b/include/media/v4l2-ctrls.h
>>> @@ -375,6 +375,7 @@ struct v4l2_ctrl_handler {
>>>   * @max:     The control's maximum value.
>>>   * @step:    The control's step value for non-menu controls.
>>>   * @def:     The control's default value.
>>> + * @p_def:   The control's default value for compound controls.
>>>   * @dims:    The size of each dimension.
>>>   * @elem_size:       The size in bytes of the control.
>>>   * @flags:   The control's flags.
>>> @@ -403,6 +404,7 @@ struct v4l2_ctrl_config {
>>>       s64 max;
>>>       u64 step;
>>>       s64 def;
>>> +     union v4l2_ctrl_ptr p_def;
>>>       u32 dims[V4L2_CTRL_MAX_DIMS];
>>>       u32 elem_size;
>>>       u32 flags;
>>>
>>
>> I'm not sure about this. It might be a bit awkward to initialize p_def given that it is a union.
>>
>> Perhaps a simple void pointer would be easier?
>>
>> Regards,
>>
>>         Hans