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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Mon, 27 Dec 2021 18:15:18 +0100
Message-ID: <CAJZ5v0htSMwM5SgSAaS-UB3G=99DC8ytQ5P4BfjDhdAoQ7pFdg@mail.gmail.com>
Subject: Re: [RFC 03/32] ACPI: Kconfig: add HAS_IOPORT dependencies
To:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Niklas Schnelle <schnelle@linux.ibm.com>
Cc:     Arnd Bergmann <arnd@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        John Garry <john.garry@huawei.com>,
        Nick Hu <nickhu@andestech.com>,
        Greentime Hu <green.hu@gmail.com>,
        Vincent Chen <deanbo422@gmail.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>, Guo Ren <guoren@kernel.org>,
        Len Brown <lenb@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Linux PCI <linux-pci@vger.kernel.org>,
        linux-riscv@lists.infradead.org, linux-csky@vger.kernel.org,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>
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On Mon, Dec 27, 2021 at 6:12 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Mon, Dec 27, 2021 at 6:02 PM Niklas Schnelle <schnelle@linux.ibm.com> wrote:
> >
> > On Mon, 2021-12-27 at 17:47 +0100, Rafael J. Wysocki wrote:
> > > On Mon, Dec 27, 2021 at 5:44 PM Niklas Schnelle <schnelle@linux.ibm.com> wrote:
> > > > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
> > > > not being declared. As ACPI always uses I/O port access
> > >
> > > The ARM64 people may not agree with this.
> >
> > Maybe my wording is bad. This is my rewording of what Arnd had in his
> > original mail: "The ACPI subsystem needs access to I/O ports, so that
> > also gets a dependency."(
> > https://lore.kernel.org/lkml/CAK8P3a0MNbx-iuzW_-=0ab6-TTZzwV-PT_6gAC1Gp5PgYyHcrA@mail.gmail.com/
> > ).
>
> And my point is that on ARM64 the ACPI subsystem does not need to
> access IO ports.
>
> It may not even need to access them on x86, but that depends on the
> platform firmware in use.
>
> If arm64 is going to set HAS_IOPORT, then fine, but is it (and this
> applies to ia64 too)?
>
> > >
> > > > we depend on HAS_IOPORT unconditionally.
> > > >
> > > > Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> > > > Signed-off-by: Arnd Bergmann <arnd@kernel.org>
> > > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> > > > ---
> > > >  drivers/acpi/Kconfig | 1 +
> > > >  1 file changed, 1 insertion(+)
> > > >
> > > > diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> > > > index cdbdf68bd98f..b57f15817ede 100644
> > > > --- a/drivers/acpi/Kconfig
> > > > +++ b/drivers/acpi/Kconfig
> > > > @@ -9,6 +9,7 @@ config ARCH_SUPPORTS_ACPI
> > > >  menuconfig ACPI
> > > >         bool "ACPI (Advanced Configuration and Power Interface) Support"
> > > >         depends on ARCH_SUPPORTS_ACPI

Besides, I'm not sure why ARCH_SUPPORTS_ACPI cannot cover this new dependency.

> > > > +       depends on HAS_IOPORT
> > > >         select PNP
> > > >         select NLS
> > > >         default y if X86
> > > > --
> > > > 2.32.0
> > > >
> >