linux-kernel - Re: [PATCH] i2c: I2C_HISI should depend on ARCH

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Message-ID: <YHW2b4aBHh3ohs8r@smile.fi.intel.com>
Date:   Tue, 13 Apr 2021 18:19:11 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Yicong Yang <yangyicong@...ilicon.com>,
        Wei Xu <xuwei5@...ilicon.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Dmitry Osipenko <digetx@...il.com>,
        Linux I2C <linux-i2c@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] i2c: I2C_HISI should depend on ARCH_HISI && ACPI

On Tue, Apr 13, 2021 at 04:44:33PM +0200, Geert Uytterhoeven wrote:
> On Tue, Apr 13, 2021 at 4:41 PM Andy Shevchenko
> <andriy.shevchenko@...ux.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@...ux.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.

It is fine, but since you add a dependency to the ARCH variant, the ACPI should
be added there, not here. Here is simply wrong place for this dependency as driver
is *not* dependent on ACPI per se.

-- 
With Best Regards,
Andy Shevchenko