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

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Date:   Wed, 14 Apr 2021 21:21:38 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
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>,
        Linuxarm <linuxarm@...wei.com>
Subject: Re: [PATCH] i2c: I2C_HISI should depend on ARCH_HISI && ACPI

Hi Andy,

On Wed, Apr 14, 2021 at 9:14 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
> On Wed, Apr 14, 2021 at 08:55:21PM +0200, Geert Uytterhoeven wrote:
> > On Wed, Apr 14, 2021 at 8:18 PM Andy Shevchenko
> > <andriy.shevchenko@...ux.intel.com> wrote:
> > > On Wed, Apr 14, 2021 at 08:06:18PM +0200, Geert Uytterhoeven wrote:
> > > > On Wed, Apr 14, 2021 at 11:24 AM Yicong Yang <yangyicong@...ilicon.com> wrote:
> > > > > On 2021/4/13 20:26, 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.
> > > > >
> > > > > this is a public IP which doesn't specifically depend on ARCH_HISI. I'm
> > > > > not sure all the platform this IP on has ARCH_HISI configured. The driver
> > > > > will not be compiled by default config. This is not correct to have
> > > > > this dependence.
> > > >
> > > > Thanks for your answer!
> > > >
> > > > I guess it's still fine to add a dependency on ACPI?
> > >
> > > But why?
> >
> > Please tell me how/when the driver is used when CONFIG_ACPI=n.
>
> I'm not using it at all. Ask the author :-)
>
> But if we follow your logic, then we need to mark all the _platform_ drivers
> for x86 world as ACPI dependent? This sounds ugly.

Do all other x86 platform drivers have (1) an .acpi_match_table[] and
(2) no other way of instantiating their devices?
The first driver from the top of my memory I looked at is rtc-cmos:
it has no .acpi_match_table[], and the rtc-cmos device is instantiated
from arch/x86/kernel/rtc.c.

For drivers with only an .of_match_table(), and no legacy users
instantiating platform devices, we do have dependencies on OF.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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