Re: [PATCH v3 6/8] media: v4l2-ctrls: Add ARGB color effects control

[Hans Verkuil <hverkuil-cisco@xs4all.nl>]

On 11/10/2021 12:00, Dillon Min wrote:
> Hi Hans
> 
> Thanks for the quick reply.
> 
> On Mon, 11 Oct 2021 at 17:40, Hans Verkuil <hverkuil-cisco@xs4all.nl> wrote:
>>
>> On 08/10/2021 12:30, dillon.minfei@gmail.com wrote:
>>> From: Dillon Min <dillon.minfei@gmail.com>
>>>
>>> - add V4L2_COLORFX_SET_ARGB color effects control.
>>> - add V4L2_CID_COLORFX_ARGB for ARGB color setting.
>>>
>>> Signed-off-by: Dillon Min <dillon.minfei@gmail.com>
>>> ---
>>> v3: according to Hans's suggestion, thanks.
>>> - remove old stm32 private R2M ioctl
>>> - add V4L2_CID_COLORFX_ARGB
>>> - add V4L2_COLORFX_SET_ARGB
>>>
>>>  Documentation/userspace-api/media/v4l/control.rst | 8 ++++++++
>>>  drivers/media/v4l2-core/v4l2-ctrls-defs.c         | 2 ++
>>>  include/uapi/linux/v4l2-controls.h                | 4 +++-
>>>  3 files changed, 13 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/userspace-api/media/v4l/control.rst b/Documentation/userspace-api/media/v4l/control.rst
>>> index f8d0b923da20..319606a6288f 100644
>>> --- a/Documentation/userspace-api/media/v4l/control.rst
>>> +++ b/Documentation/userspace-api/media/v4l/control.rst
>>> @@ -242,8 +242,16 @@ Control IDs
>>>      * - ``V4L2_COLORFX_SET_CBCR``
>>>        - The Cb and Cr chroma components are replaced by fixed coefficients
>>>       determined by ``V4L2_CID_COLORFX_CBCR`` control.
>>> +    * - ``V4L2_COLORFX_SET_ARGB``
>>> +      - ARGB colors.
>>
>> How about:
>>
>>         - The ARGB components are replaced by the fixed ARGB components
>>         determined by ``V4L2_CID_COLORFX_ARGB`` control.
> 
> Sure, will be addressed by v4.
> 
>>
>> I also wonder if it makes sense to include the alpha channel here.
>>
>> Looking at the driver code it appears to me (I might be wrong) that the alpha
>> channel is never touched (DMA2D_ALPHA_MODE_NO_MODIF), and setting the alpha
>> channel as part of a color effects control is rather odd as well.
> 
> Indeed, Alpha channel is not used in current code. I'll remove this item in v4.
> how about change the code like below:
> 
>     * - ``V4L2_COLORFX_SET_RGB``
>        - The RGB components are replaced by the fixed RGB components
>          determined by ``V4L2_CID_COLORFX_RGB`` control.
> 
> ``V4L2_CID_COLORFX_RGB`` ``(integer)``
>     Determines the Red, Green, and Blue coefficients for
>     ``V4L2_COLORFX_SET_RGB`` color effect.
>     Bits [7:0] of the supplied 32 bit value are interpreted as Blue component,
>     bits [15:8] as Green component, bits [23:16] as Red component, and
>     bits [31:24] must be zero.

Yes, that looks OK to me.

Regards,

	Hans

> 
> 
>>
>> Alpha channel manipulation really is separate from the color and - if needed - should
>> be done with a separate control.
> 
> OK, Will use a separate control when adding blend features.
> 
> Best Regards,
> Dillon
> 
>>
>> Regards,
>>
>>         Hans
>>
>>>
>>>
>>> +``V4L2_CID_COLORFX_ARGB`` ``(integer)``
>>> +    Determines the Alpha, Red, Green, and Blue coefficients for
>>> +    ``V4L2_COLORFX_SET_ARGB`` color effect.
>>> +    Bits [7:0] of the supplied 32 bit value are interpreted as Blue component,
>>> +    bits [15:8] as Green component, bits [23:16] as Red component, and
>>> +    bits [31:24] as Alpha component.
>>>
>>>  ``V4L2_CID_COLORFX_CBCR`` ``(integer)``
>>>      Determines the Cb and Cr coefficients for ``V4L2_COLORFX_SET_CBCR``
>>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
>>> index 421300e13a41..53be6aadb289 100644
>>> --- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
>>> +++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
>>> @@ -785,6 +785,7 @@ const char *v4l2_ctrl_get_name(u32 id)
>>>       case V4L2_CID_MIN_BUFFERS_FOR_OUTPUT:   return "Min Number of Output Buffers";
>>>       case V4L2_CID_ALPHA_COMPONENT:          return "Alpha Component";
>>>       case V4L2_CID_COLORFX_CBCR:             return "Color Effects, CbCr";
>>> +     case V4L2_CID_COLORFX_ARGB:             return "Color Effects, ARGB";
>>>
>>>       /*
>>>        * Codec controls
>>> @@ -1392,6 +1393,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
>>>               *min = *max = *step = *def = 0;
>>>               break;
>>>       case V4L2_CID_BG_COLOR:
>>> +     case V4L2_CID_COLORFX_ARGB:
>>>               *type = V4L2_CTRL_TYPE_INTEGER;
>>>               *step = 1;
>>>               *min = 0;
>>> diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
>>> index 5532b5f68493..2876c2282a68 100644
>>> --- a/include/uapi/linux/v4l2-controls.h
>>> +++ b/include/uapi/linux/v4l2-controls.h
>>> @@ -128,6 +128,7 @@ enum v4l2_colorfx {
>>>       V4L2_COLORFX_SOLARIZATION               = 13,
>>>       V4L2_COLORFX_ANTIQUE                    = 14,
>>>       V4L2_COLORFX_SET_CBCR                   = 15,
>>> +     V4L2_COLORFX_SET_ARGB                   = 16,
>>>  };
>>>  #define V4L2_CID_AUTOBRIGHTNESS                      (V4L2_CID_BASE+32)
>>>  #define V4L2_CID_BAND_STOP_FILTER            (V4L2_CID_BASE+33)
>>> @@ -145,9 +146,10 @@ enum v4l2_colorfx {
>>>
>>>  #define V4L2_CID_ALPHA_COMPONENT             (V4L2_CID_BASE+41)
>>>  #define V4L2_CID_COLORFX_CBCR                        (V4L2_CID_BASE+42)
>>> +#define V4L2_CID_COLORFX_ARGB                        (V4L2_CID_BASE+43)
>>>
>>>  /* last CID + 1 */
>>> -#define V4L2_CID_LASTP1                         (V4L2_CID_BASE+43)
>>> +#define V4L2_CID_LASTP1                         (V4L2_CID_BASE+44)
>>>
>>>  /* USER-class private control IDs */
>>>
>>>
>>