LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Jeremy Linton <jeremy.linton@arm.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: linux-pci@vger.kernel.org, lorenzo.pieralisi@arm.com,
	nsaenz@kernel.org, bhelgaas@google.com, rjw@rjwysocki.net,
	lenb@kernel.org, robh@kernel.org, kw@linux.com,
	f.fainelli@gmail.com, bcm-kernel-feedback-list@broadcom.com,
	linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-rpi-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] PCI: brcmstb: Add ACPI config space quirk
Date: Mon, 9 Aug 2021 14:48:17 -0500	[thread overview]
Message-ID: <4d4732b9-e8df-3803-2db7-c6eef1196269@arm.com> (raw)
In-Reply-To: <20210809174244.GA2167737@bjorn-Precision-5520>

Hi,

On 8/9/21 12:42 PM, Bjorn Helgaas wrote:
> On Fri, Aug 06, 2021 at 09:55:27PM -0500, Jeremy Linton wrote:
>> Hi,
>>
>> On 8/6/21 5:21 PM, Bjorn Helgaas wrote:
>>> On Thu, Aug 05, 2021 at 04:11:59PM -0500, Jeremy Linton wrote:
>>>> The PFTF CM4 is an ACPI platform that is following the PCIe SMCCC
>>>> standard because its PCIe config space isn't ECAM compliant and is
>>>> split into two parts. One part for the root port registers and a
>>>> moveable window which points at a given device's 4K config space.
>>>> Thus it doesn't have a MCFG (and really any MCFG provided would be
>>>> nonsense anyway). As Linux doesn't support the PCIe SMCCC standard
>>>> we key off a Linux specific host bridge _DSD to add custom ECAM
>>>> ops and cfgres. The cfg op selects between those two regions, as
>>>> well as disallowing problematic accesses, particularly if the link
>>>> is down because there isn't an attached device.
>>>
>>> I'm not sure SMCCC is *really* relevant here.  If it is, an expansion
>>> of the acronym and a link to a spec would be helpful.
>>>
>>> But AFAICT the only important thing here is that it doesn't have
>>> standard ECAM, and we're going to work around that.
>>
>> I will reword it a bit.
>>
>>> I don't see anything about _DSD in this series.
>>
>> That is the "linux,pci-quirk" in the next patch.
> 
> The next patch doesn't mention _DSD either.  Is it obfuscated by
> being inside fwnode_property_read_string()?  If so, it's well and
> truly hidden; I gave up trying to connect that with ACPI.

Right, the fwnode stuff works as a DT/ACPI abstraction for reading 
values from firmware tables. In this case the ACPI definition looks 
something like:

Device(PCI0) {
...
   Name (_DSD, Package () {
   ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
     Package () {
     Package () { "linux-pcie-quirk", "bcm2711" },
   }
   })

...
}

Which explains a bit of why the underlying code is a bit uh... complicated.

  reply	other threads:[~2021-08-09 19:48 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05 21:11 [PATCH 0/3] CM4 ACPI PCIe quirk Jeremy Linton
2021-08-05 21:11 ` [PATCH 1/3] PCI: brcmstb: Break register definitions into separate header Jeremy Linton
2021-08-10 10:07   ` Florian Fainelli
2021-08-10 15:10     ` Jeremy Linton
2021-08-11  8:39       ` Florian Fainelli
2021-08-05 21:11 ` [PATCH 2/3] PCI: brcmstb: Add ACPI config space quirk Jeremy Linton
2021-08-06 22:21   ` Bjorn Helgaas
2021-08-07  2:55     ` Jeremy Linton
2021-08-09 17:42       ` Bjorn Helgaas
2021-08-09 19:48         ` Jeremy Linton [this message]
2021-08-09 20:33           ` Bjorn Helgaas
2021-08-09 21:21             ` Jeremy Linton
2021-08-05 21:12 ` [PATCH 3/3] PCI/ACPI: Add new quirk detection, enable bcm2711 Jeremy Linton
2021-08-06 22:12   ` Bjorn Helgaas
2021-08-07  0:34     ` Jeremy Linton
2021-08-09 15:27       ` Rob Herring
2021-08-09 16:24         ` Jeremy Linton
2021-08-10 14:31   ` Shanker R Donthineni
2021-08-10 14:47     ` Jeremy Linton
2021-08-10 15:09       ` Shanker R Donthineni
2021-08-06 11:40 ` [PATCH 0/3] CM4 ACPI PCIe quirk Stefan Wahren

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4d4732b9-e8df-3803-2db7-c6eef1196269@arm.com \
    --to=jeremy.linton@arm.com \
    --cc=bcm-kernel-feedback-list@broadcom.com \
    --cc=bhelgaas@google.com \
    --cc=f.fainelli@gmail.com \
    --cc=helgaas@kernel.org \
    --cc=kw@linux.com \
    --cc=lenb@kernel.org \
    --cc=linux-acpi@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=linux-rpi-kernel@lists.infradead.org \
    --cc=lorenzo.pieralisi@arm.com \
    --cc=nsaenz@kernel.org \
    --cc=rjw@rjwysocki.net \
    --cc=robh@kernel.org \
    --subject='Re: [PATCH 2/3] PCI: brcmstb: Add ACPI config space quirk' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).