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From: Will Deacon <will@kernel.org>
To: Jeremy Linton <jeremy.linton@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
	lorenzo.pieralisi@arm.com, bhelgaas@google.com,
	catalin.marinas@arm.com, robh@kernel.org, sudeep.holla@arm.com,
	mark.rutland@arm.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: PCI: Enable SMC conduit
Date: Thu, 7 Jan 2021 18:14:17 +0000	[thread overview]
Message-ID: <20210107181416.GA3536@willie-the-truck> (raw)
In-Reply-To: <20210105045735.1709825-1-jeremy.linton@arm.com>

On Mon, Jan 04, 2021 at 10:57:35PM -0600, Jeremy Linton wrote:
> Given that most arm64 platform's PCI implementations needs quirks
> to deal with problematic config accesses, this is a good place to
> apply a firmware abstraction. The ARM PCI SMMCCC spec details a
> standard SMC conduit designed to provide a simple PCI config
> accessor. This specification enhances the existing ACPI/PCI
> abstraction and expects power, config, etc functionality is handled
> by the platform. It also is very explicit that the resulting config
> space registers must behave as is specified by the pci specification.
> 
> Lets hook the normal ACPI/PCI config path, and when we detect
> missing MADT data, attempt to probe the SMC conduit. If the conduit
> exists and responds for the requested segment number (provided by the
> ACPI namespace) attach a custom pci_ecam_ops which redirects
> all config read/write requests to the firmware.
> 
> This patch is based on the Arm PCI Config space access document @
> https://developer.arm.com/documentation/den0115/latest

Why does firmware need to be involved with this at all? Can't we just
quirk Linux when these broken designs show up in production? We'll need
to modify Linux _anyway_ when the firmware interface isn't implemented
correctly...

Will

  parent reply	other threads:[~2021-01-07 18:15 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-05  4:57 [PATCH] arm64: PCI: Enable SMC conduit Jeremy Linton
2021-01-07 15:28 ` Rob Herring
2021-01-07 16:23   ` Jeremy Linton
2021-01-07 17:36     ` Rob Herring
2021-01-07 19:45       ` Jeremy Linton
2021-01-07 20:35         ` Rob Herring
2021-01-07 18:14 ` Will Deacon [this message]
2021-01-07 19:18   ` Jeremy Linton
2021-01-07 21:05   ` Jon Masters
2021-01-07 21:49     ` Rob Herring
2021-01-08 10:32     ` Lorenzo Pieralisi
2021-01-22 19:48       ` Will Deacon
2021-01-26 16:46         ` Jeremy Linton
2021-01-26 22:54           ` Will Deacon
2021-01-28 18:50             ` Jeremy Linton
2021-01-28 23:31           ` Bjorn Helgaas
     [not found]             ` <CACCGGCc3zULqHgUh3Q9wA5WtPBnQ4eq_v2+1qA8bOBCQZJ5YoQ@mail.gmail.com>
2021-02-25  9:30               ` Lorenzo Pieralisi
2021-02-25 22:31                 ` Jeremy Linton
2021-01-26 17:08         ` Vikram Sethi
2021-01-26 22:53           ` Will Deacon
2021-03-25 13:12             ` Lorenzo Pieralisi
2021-03-25 20:45               ` Marcin Wojtas
2021-03-25 21:12                 ` Jon Masters
2021-03-26  9:27                   ` Marcin Wojtas
2021-06-16 17:36               ` Jason Gunthorpe
     [not found]                 ` <CA+kK7ZijdNERQSauEvAffR7JLbfZ512na2-9cJrU0vFbNnDGwQ@mail.gmail.com>
2021-06-18 14:05                   ` Jason Gunthorpe
2021-06-19 16:34                     ` Jon Masters
2021-06-19 16:38                       ` Jon Masters
2021-06-20  0:26                       ` Jason Gunthorpe
2021-06-18 15:10               ` Jeremy Linton
2021-01-12 16:16 ` Vidya Sagar
2021-01-12 16:57   ` Jeremy Linton

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