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Message-ID: <alpine.DEB.2.21.2207222328230.48997@angie.orcam.me.uk>
Date: Fri, 22 Jul 2022 23:41:54 +0100 (BST)
From: "Maciej W. Rozycki" <macro@...am.me.uk>
To: Rob Herring <robh@...nel.org>
cc: Arnd Bergmann <arnd@...db.de>, Palmer Dabbelt <palmer@...belt.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Stafford Horne <shorne@...il.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Catalin Marinas <catalin.marinas@....com>,
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Paul Walmsley <paul.walmsley@...ive.com>,
Albert Ou <aou@...s.berkeley.edu>,
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Anton Ivanov <anton.ivanov@...bridgegreys.com>,
Johannes Berg <johannes@...solutions.net>,
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"open list:GENERIC INCLUDE/ASM HEADER FILES"
<linux-arch@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] asm-generic: Add new pci.h and use it
On Fri, 22 Jul 2022, Rob Herring wrote:
> P.S. I really wish I/O space would disappear completely.
Some systems make it happen already, such as the POWER9 platform and its
PHB4 host bridge (which doesn't handle PCIe TLP I/O read or write commands
at all), however some PCI/e devices do require I/O space, such as IEEE
1284 parallel port adapters. Some PCI devices dating back as far as to
1990s provide dual mapping of their resources via an I/O and a memory BAR
both at a time, so we can choose which to use depending on circumstances.
FWIW,
Maciej
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