[PATCH] ipa: rpi: Fix wrong frame integration difference value for OV9281

[Dave Stevenson]

On Mon, 9 Dec 2024 at 12:56, Kieran Bingham
<kieran.bingham at ideasonboard.com> wrote:
>
> Quoting Naushir Patuck (2024-12-09 10:47:23)
> > The frameIntegrationDiff value should be 25, otherwise we see invalid
> > frames when integration times are set to large values.
> >
> > Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> > ---
> >  src/ipa/rpi/cam_helper/cam_helper_ov9281.cpp | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/src/ipa/rpi/cam_helper/cam_helper_ov9281.cpp b/src/ipa/rpi/cam_helper/cam_helper_ov9281.cpp
> > index a65c8ac08c1c..96f7fff499f5 100644
> > --- a/src/ipa/rpi/cam_helper/cam_helper_ov9281.cpp
> > +++ b/src/ipa/rpi/cam_helper/cam_helper_ov9281.cpp
> > @@ -25,7 +25,7 @@ private:
> >          * Smallest difference between the frame length and integration time,
> >          * in units of lines.
> >          */
> > -       static constexpr int frameIntegrationDiff = 4;
> > +       static constexpr int frameIntegrationDiff = 25;
>
> Aha, quite helpfully - Laurent just pointed out to me that this is
> specified in the datasheet as

Probably as I'd just sent him a link to the datasheet :-)

> 0x3502 EXPO 0x00 RW
>
> Bit[7:0]: Exposure[7:0]
>         Low 4 bits are fraction bits
>
> Minimum exposure time is 1 row period.
> Maximum exposure time is frame length -25 row
>         periods, where frame length is set by registers
>         {0x380E, 0x380F}
>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

Matching kernel commit submitted as
https://lore.kernel.org/linux-media/20241209-media-ov9282-fix-v1-1-d06bb7546f18@raspberrypi.com/

  Dave

> >  };
> >
> >  /*
> > --
> > 2.43.0
> >