linux-kernel - Re: [PATCH v4 1/2] ACPI / x86: boot: Not all platforms require acpi_reduced_hw

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Message-ID: <1519147549.10722.2.camel@linux.intel.com>
Date:   Tue, 20 Feb 2018 19:25:49 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "H . Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Juergen Gross <jgross@...e.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/2] ACPI / x86: boot: Not all platforms require
 acpi_reduced_hw_init()

On Tue, 2018-02-20 at 17:27 +0100, Rafael J. Wysocki wrote:
> On Tue, Feb 20, 2018 at 5:03 PM, Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com> wrote:
> > Some platforms might take care of legacy devices on theirs own. Due
> > to this,
> > export acpi_reduced_hw_init() and put it into struct x86_init_acpi.
> 
> IMO this completely doesn't explain what really happens here.
> 
> You basically want to provide your own versions of
> x86_init.timers.timer_init, x86_init.irqs.pre_vector_init and
> legacy_pic on some HW-reduced platforms AFAICS, so you make it
> possible for the platform to provide its own variant of
> acpi_reduced_hw_init().

In this particular case only timers matter, though in general you are
right.

> I would say something like this:
> 
> "Some ACPI hawdware-reduced platforms need to initialize certain
> devices defined by the ACPI hardware specification even though in
> principle those devices should not be present in an ACPI
> hawdware-reduced platform.  To allow that to happen, make it possible
> to override the generic x86_init callbacks and provide a custom
> legacy_pic value, add a new ->reduced_hw_early_init() callback to
> struct x86_init_acpi and make acpi_reduced_hw_init() use it."

Thanks for review! I will use your suggestions in the next version.

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy