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From:   Gonsolo <gonsolo@gmail.com>
Date:   Wed, 2 Oct 2019 16:44:24 +0200
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Subject: Re: [PATCH] si2157: Add support for Logilink VG0022A.
To:     Sean Young <sean@mess.org>
Cc:     mchehab+samsung@kernel.org, crope@iki.fi,
        linux-media@vger.kernel.org,
        Linux Kernel <linux-kernel@vger.kernel.org>
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Hi!

> You need a message and a Signed-off-by: here.

Ok, I'll try to get that right the next time.

> > +     ret = si2157_power_up(dev, client);
> > +     if (ret)
> > +             goto err;
> > +     /* query chip revision */
> > +     /* hack: do it here because after the si2168 gets 0101, commands will
> > +      * still be executed here but no result
>
> I don't understand. What problem are you seeing here? Why can't you do a
> query chip revision first?

This was explained here: https://lkml.org/lkml/2017/3/15/778. To quote:

If the si2157 is behind a e.g. si2168, the si2157 will at least in
some situations not be readable after the si268 got the command 0101.
It still accepts commands but the answer is just ffffff. So read the
chip id before that so the information is not lost.

The following line in kernel output is a symptome of that problem:
si2157 7-0063: unknown chip version Si21255-\xffffffff\xffffffff\xffffffff

> This needs resolving of course.

I hope so. :)

g