Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220429135108.2781579-44-schnelle@linux.ibm.com>
 <20220503233802.GA420374@bhelgaas> <CAK8P3a02vidd7u5Kp6UJj=9tj_hFGL24SmzuNpDGu1GOa1w9+w@mail.gmail.com>
 <alpine.DEB.2.21.2205041311280.9548@angie.orcam.me.uk>
In-Reply-To: <alpine.DEB.2.21.2205041311280.9548@angie.orcam.me.uk>
From:   Arnd Bergmann <arnd@kernel.org>
Date:   Wed, 4 May 2022 16:07:09 +0200
Message-ID: <CAK8P3a2jwv00En13=5mHVA4OGRzDpAsPKy4nqM79L6xP5=aQFQ@mail.gmail.com>
Subject: Re: [RFC v2 25/39] pcmcia: add HAS_IOPORT dependencies
To:     "Maciej W. Rozycki" <macro@orcam.me.uk>
Cc:     Bjorn Helgaas <helgaas@kernel.org>,
        Niklas Schnelle <schnelle@linux.ibm.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        linux-pci <linux-pci@vger.kernel.org>,
        Dominik Brodowski <linux@dominikbrodowski.net>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Wed, May 4, 2022 at 2:38 PM Maciej W. Rozycki <macro@orcam.me.uk> wrote:
>
> On Wed, 4 May 2022, Arnd Bergmann wrote:
>
> > Almost all architectures that support CONFIG_PCI also provide
> > HAS_IOPORT today (at least at compile time, if not at runtime),
> > with s390 as a notable exception. Any machines that have legacy
> > PCI device support will also have I/O ports because a lot of
> > legacy PCI cards used it, and any machine with a pc-card slot
> > should also support legacy PCI devices.
> >
> > If we get new architectures without I/O space in the future, they
> > would certainly not care about supporting old cardbus devices.
>
>  POWER9 is another architecture with no port I/O space[1]:

POWER9 is just an implementation of the power architecture
that has a particular PCI host bridge. I would assume that
arch/powerpc/ would continue to set HAS_IOPORT because
it knows how to access I/O ports at compile-time.

If a particular host bridge does not declare an I/O port range
in its DT, then of course it won't be accessible, but that is
different from architectures that have no concept of I/O ports.

         Arnd