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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Mon, 27 Dec 2021 18:12:39 +0100
Message-ID: <CAJZ5v0iG=wqVtJULiTFsffMWqihA0Rk+abMzmfTcH+J9d5G+YA@mail.gmail.com>
Subject: Re: [RFC 03/32] ACPI: Kconfig: add HAS_IOPORT dependencies
To:     Niklas Schnelle <schnelle@linux.ibm.com>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        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 6:02 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
> > > +       depends on HAS_IOPORT
> > >         select PNP
> > >         select NLS
> > >         default y if X86
> > > --
> > > 2.32.0
> > >
>