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

[Dillon Min <dillon.minfei@gmail.com>]

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.


>
> 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 */
> >
> >
>