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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Tue, 13 Apr 2021 16:44:33 +0200
Message-ID: <CAMuHMdV1kTcPhutZZa04zd53C37Ci7Fr51nq1z8OX3kg1C14CA@mail.gmail.com>
Subject: Re: [PATCH] i2c: I2C_HISI should depend on ARCH_HISI && ACPI
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     Yicong Yang <yangyicong@hisilicon.com>,
        Wei Xu <xuwei5@hisilicon.com>,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Dmitry Osipenko <digetx@gmail.com>,
        Linux I2C <linux-i2c@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Hi Andy,

On Tue, Apr 13, 2021 at 4:41 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
> On Tue, Apr 13, 2021 at 02:48:15PM +0200, Geert Uytterhoeven wrote:
> > On Tue, Apr 13, 2021 at 2:37 PM Andy Shevchenko
> > <andriy.shevchenko@linux.intel.com> wrote:
> > > On Tue, Apr 13, 2021 at 02:26:15PM +0200, Geert Uytterhoeven wrote:
> > > > The HiSilicon Kunpeng I2C controller is only present on HiSilicon
> > > > Kunpeng SoCs, and its driver relies on ACPI to probe for its presence.
> > > > Hence add dependencies on ARCH_HISI and ACPI, to prevent asking the user
> > > > about this driver when configuring a kernel without Hisilicon platform
> > > > or ACPI firmware support.
> > >
> > > I don't by the ACPI dependency, sorry.
> > >
> > > The driver is a pure platform driver that can be enumerated on ACPI enabled
> > > devices, but otherwise it can be used as a platform one.
> >
> > Sure, you can manually instantiate a platform device with a matching
> > name, and set up the "clk_rate" device property.
> > But would it make sense to do that? Would anyone ever do that?
>
> It will narrow down the possibility to have One Kernel for as many as possible
> platforms.

That One Kernel needs to have CONFIG_ACPI enabled to use I2C on the
HiSilicon Kunpeng.  If CONFIG_ACPI is disabled, it cannot be used, as there
is no other code that creates "hisi-i2c" platform devices.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds