linux-kernel - Re: [PATCHv3 3/6] media: v4l UAPI: add ROI auto-controls flags

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Message-ID: <YFqiWixqSuPMTwXz@google.com>
Date:   Wed, 24 Mar 2021 11:22:18 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Ricardo Ribalda <ribalda@...omium.org>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Tomasz Figa <tfiga@...omium.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv3 3/6] media: v4l UAPI: add ROI auto-controls flags

On (21/03/23 17:04), Ricardo Ribalda wrote:
> On Fri, Mar 19, 2021 at 6:53 AM Sergey Senozhatsky
> <senozhatsky@...omium.org> wrote:
> >
> > UVC 1.5 defines the following Region Of Interest auto controls:
> >
> > D0: Auto Exposure
> > D1: Auto Iris
> > D2: Auto White Balance
> > D3: Auto Focus
> > D4: Auto Face Detect
> > D5: Auto Detect and Track
> > D6: Image Stabilization
> > D7: Higher Quality
> > D8 – D15: Reserved, set to zero
> >
> > Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
> > ---
> >  include/uapi/linux/v4l2-common.h | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/include/uapi/linux/v4l2-common.h b/include/uapi/linux/v4l2-common.h
> > index 3651ebb8cb23..34f1c262d6aa 100644
> > --- a/include/uapi/linux/v4l2-common.h
> > +++ b/include/uapi/linux/v4l2-common.h
> > @@ -92,6 +92,16 @@
> >  #define V4L2_SEL_FLAG_LE               (1 << 1)
> >  #define V4L2_SEL_FLAG_KEEP_CONFIG      (1 << 2)
> >
> 
> Are you sure that you do not want to start with 1<<3, there might be
> some hardware that support LE/SE

How the hardware's going to support this? There is simply no way to
pass these flags to the firmware, the values already overlap with
auto-controls. So I guess these flags are for the driver (C code).
uvcvideo driver is not doing any "lesser or equal rectangle" magic
for ROI. No such thing is defined by UVC spec.

I can move these flags to entirely different value range and do
remapping to uvc auto-controls values in uvcvideo.