Re: [PATCH v2 4/4] media: staging: rkisp1: cap: remove support of BGR666 format

[Tomasz Figa <tfiga@chromium.org>]

On Thu, May 21, 2020 at 12:35 AM Helen Koike <helen.koike@collabora.com> wrote:
>
>
>
> On 5/15/20 11:29 AM, Dafna Hirschfeld wrote:
> > The rkisp1 supports RGB encoding with 6 bits per
> > color with the following format:
> > - - b5 b4 b3 b2 b1 b0 - - g5 g4 g3 g2 g1 g0 - - r5 r4 r3 r2 r1 r0 - - - - - - - -
>
> Is this the same as V4L2_PIX_FMT_XBGR32 format, but with colors range from 0 to 63 ?
>
> I was wondering what is the usage of such a format. If it is useful, then I'm sad
> to see this being removed from the driver, since this is a v4l2 api limitation, and not
> a hw limitation.

Sounds like some relic of the past. ;)

In general, RGB formats are not very useful in this hardware. One
wastes the precious bandwidth, but doesn't get more color resolution,
since the pipeline uses YUV 4:2:2 internally anyway. The typical usage
scenarios with video or JPEG encoding and preview are much better off
with the available YUV formats.

>
> Regards,
> Helen
>
> >
> > This is not how V4L2_PIX_FMT_BGR666 is defined, so remove
> > this format from the driver's formats list.
> >
> > Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
> > ---
> >  drivers/staging/media/rkisp1/rkisp1-capture.c | 4 ----
> >  1 file changed, 4 deletions(-)
> >
> > diff --git a/drivers/staging/media/rkisp1/rkisp1-capture.c b/drivers/staging/media/rkisp1/rkisp1-capture.c
> > index 61b9ebe577b2..2660e44eda88 100644
> > --- a/drivers/staging/media/rkisp1/rkisp1-capture.c
> > +++ b/drivers/staging/media/rkisp1/rkisp1-capture.c
> > @@ -283,10 +283,6 @@ static const struct rkisp1_capture_fmt_cfg rkisp1_sp_fmts[] = {
> >               .fourcc = V4L2_PIX_FMT_RGB565,
> >               .write_format = RKISP1_MI_CTRL_SP_WRITE_PLA,
> >               .output_format = RKISP1_MI_CTRL_SP_OUTPUT_RGB565,
> > -     }, {
> > -             .fourcc = V4L2_PIX_FMT_BGR666,
> > -             .write_format = RKISP1_MI_CTRL_SP_WRITE_PLA,
> > -             .output_format = RKISP1_MI_CTRL_SP_OUTPUT_RGB666,
> >       },
> >  };
> >
> >