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Date:   Mon, 3 Aug 2020 21:21:08 +0200
From:   Niklas <niklas.soderlund@ragnatech.se>
To:     "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Cc:     Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
        linux-media <linux-media@vger.kernel.org>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Biju Das <biju.das.jz@bp.renesas.com>
Subject: Re: [PATCH] media: rcar-vin: Update crop and compose settings for
 every s_fmt call
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Hi Lad, Hans,

On 2020-08-03 19:11:32 +0100, Lad, Prabhakar wrote:
> Hi Hans,
> 
> On Sat, Aug 1, 2020 at 10:04 AM Niklas <niklas.soderlund@ragnatech.se> wrote:
> >
> > Hi Lad,
> >
> > Thanks for your work.
> >
> > On 2020-07-31 10:29:05 +0100, Lad Prabhakar wrote:
> > > The crop and compose settings for VIN in non mc mode werent updated
> > > in s_fmt call this resulted in captured images being clipped.
> > >
> > > With the below sequence on the third capture where size is set to
> > > 640x480 resulted in clipped image of size 320x240.
> > >
> > > high(640x480) -> low (320x240) -> high (640x480)
> > >
> > > This patch makes sure the VIN crop and compose settings are updated.
> >
> > This is clearly an inconsistency in the VIN driver that should be fixed.
> > But I think the none-mc mode implements the correct behavior. That is
> > that S_FMT should not modify the crop/compose rectangles other then make
> > sure they don't go out of bounds. This is an area we tried to clarify in
> > the past but I'm still not sure what the correct answer to.
> >
> What should be the exact behaviour of the bridge driver  for s_fmt
> call. Should the crop/compose settings be updated for every s_fmt
> callback or should they be only updated on s_selection callback.
> Currently the non-mc rcar-vin doesnt update the crop/compose setting
> in s_fmt callback due to which I see the above issue as mentioned.

This is not entirely correct. It does update the crop and compose 
rectangles on s_fmt, it makes sure they are not out-of-bounds for the 
new format if it's accepted by s_fmt. See v4l2_rect_map_inside() calls 
in the snippet bellow.

That being said there is a difference how this is handled in the VIN 
driver between it's MC and non-MC modes and I would love to learn the 
correct mode of operation and seeing VIN being updated to doing it 
correct in both cases. Thanks Lad for dealing with this!

> 
> Cheers,
> Prabhakar
> 
> > >
> > > Fixes: 104464f573d ("media: rcar-vin: Do not reset the crop and compose rectangles in s_fmt")
> > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > > Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
> > > ---
> > >  drivers/media/platform/rcar-vin/rcar-v4l2.c | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/drivers/media/platform/rcar-vin/rcar-v4l2.c b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> > > index f421e25..a9b13d9 100644
> > > --- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> > > +++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> > > @@ -319,6 +319,12 @@ static int rvin_s_fmt_vid_cap(struct file *file, void *priv,
> > >       fmt_rect.width = vin->format.width;
> > >       fmt_rect.height = vin->format.height;
> > >
> > > +     vin->crop.top = 0;
> > > +     vin->crop.left = 0;
> > > +     vin->crop.width = vin->format.width;
> > > +     vin->crop.height = vin->format.height;
> > > +     vin->compose = vin->crop;
> > > +
> > >       v4l2_rect_map_inside(&vin->crop, &src_rect);
> > >       v4l2_rect_map_inside(&vin->compose, &fmt_rect);
> > >       vin->src_rect = src_rect;
> > > --
> > > 2.7.4
> > >
> >
> > --
> > Regards,
> > Niklas S?derlund

-- 
Regards,
Niklas S?derlund