Message-ID: <CAGb2v65t6kO9HfSTuXZsBu6Pyc+mueLq-5tsYsw9vxwg5o=v4A@mail.gmail.com>
Date:   Tue, 22 Jan 2019 01:39:26 +0800
From:   Chen-Yu Tsai <wens@...e.org>
To:     Jernej Škrabec <jernej.skrabec@...l.net>
Cc:     Maxime Ripard <maxime.ripard@...tlin.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH 1/3] media: dt: bindings: sunxi-ir: Add A64 compatible

On Tue, Jan 22, 2019 at 1:33 AM Jernej Škrabec <jernej.skrabec@...l.net> wrote:
>
> Dne ponedeljek, 21. januar 2019 ob 10:57:57 CET je Chen-Yu Tsai napisal(a):
> > On Mon, Jan 21, 2019 at 5:50 PM Maxime Ripard <maxime.ripard@...tlin.com>
> wrote:
> > > Hi,
> > >
> > > I'm a bit late to the party, sorry for that.
> > >
> > > On Sat, Jan 12, 2019 at 09:56:11AM +0800, Chen-Yu Tsai wrote:
> > > > On Sat, Jan 12, 2019 at 1:30 AM Jernej Skrabec <jernej.skrabec@...l.net>
> wrote:
> > > > > A64 IR is compatible with A13, so add A64 compatible with A13 as a
> > > > > fallback.
> > > >
> > > > We ask people to add the SoC-specific compatible as a contigency,
> > > > in case things turn out to be not so "compatible".
> > > >
> > > > To be consistent with all the other SoCs and other peripherals,
> > > > unless you already spotted a "compatible" difference in the
> > > > hardware, i.e. the hardware isn't completely the same, this
> > > > patch isn't needed. On the other hand, if you did, please mention
> > > > the differences in the commit log.
> > >
> > > Even if we don't spot things, since we have the stable DT now, if we
> > > ever had that compatible in the DT from day 1, it's much easier to
> > > deal with.
> > >
> > > I'd really like to have that pattern for all the IPs even if we didn't
> > > spot any issue, since we can't really say that the datasheet are
> > > complete, and one can always make a mistake and overlook something.
> > >
> > > I'm fine with this version, and can apply it as is if we all agree.
> >
> > I'm OK with having the fallback compatible. I'm just pointing out
> > that there are and will be a whole bunch of them, and we don't need
> > to document all of them unless we are actually doing something to
> > support them.
>
> If you don't document them, checkpatch will complain. But if you can live with
> this warning, that's fine by me.
>
> >
> > On the other hand, the compatible string situation for IR needs a
> > bit of cleaning up at the moment. Right now we have sun4i-a10 and
> > sun5i-a13. As Jernej pointed out, the A13's register definition is
> > different from A64 (or any other SoCs later than sun6i). So we need
> > someone with an A10s/A13 device that has IR to test it and see if
> > the driver or the manual is wrong, and we'd likely add a compatible
> > for the A20.
> >
> > Also, the earlier SoCs (A10/sun5i/A20) have IR TX capability. This
> > was lost in A31, and also all of sun8i / sun50i. So we're going to
> > need to add an A31 compatible that all later platforms would need
> > to switch to.
> >
>
> H6 has IR TX peripheral too, but it's different IP block...
>
> Do you want me to switch all A31 and newer to different compatible in this
> series? I can do this, but I haven't any A13 device to test if this is really
> needed. Or you can argue that this is needed anyway due to missing TX
> capability.

The lack of TX capability does necessitate switching to an A31 compatible.
So yes, please switch. Lets leave the A10s/A13 alone for now, unless
someone complains. I think this was done from inception, so if it was
broken, someone should've complained a long time ago. I just want to
be sure where the error is, and put in a comment explaining it. However
I don't have the hardware either.

ChenYu

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