linux-kernel - Re: [PATCH v2 1/3] PCI: dwc: Fix skipped index 0 in outbound ATU setup

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Message-ID: <aXKUW8euDVaRJofR@ryzen>
Date: Thu, 22 Jan 2026 22:19:23 +0100
From: Niklas Cassel <cassel@...nel.org>
To: "Maciej W. Rozycki" <macro@...am.me.uk>
Cc: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>,
	Jingoo Han <jingoohan1@...il.com>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Frank Li <Frank.Li@....com>,
	Serge Semin <Sergey.Semin@...kalelectronics.ru>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH v2 1/3] PCI: dwc: Fix skipped index 0 in outbound ATU
 setup

On Thu, Jan 22, 2026 at 06:16:11PM +0000, Maciej W. Rozycki wrote:
> On Thu, 22 Jan 2026, Niklas Cassel wrote:
> 
> > Also see my series here:
> > https://lore.kernel.org/linux-pci/20260122145411.453291-4-cassel@kernel.org/T/
> > 
> > That tries to clean up this mess.
> 
>  Is your patchset referred meant to replace this one or does it apply on 
> top?

This series does no longer apply, as it collides with a commit queued on
controller/dwc branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?h=controller/dwc&id=e9a5415adb209f86a05e55b850127ada82e070f1

My patches are based on top of the above commit.
(I saw the big mess we currently have with regards to iatu indexing,
so I decided to clean it up, but making things consistent.)

So first of all, this series needs to be rebased.
If you ask me personally, I would prefer if Krishna could rebase on top
of my cleanups.

Patch 1/3 in this series is simply wrong, so it should be dropped.

Patch 2/3 in this series is similar to patch 1/3 in my series, but seems
to also have some extra prints that seem to be unrelated to fixing the issue
at hand. (Fine to add extra prints in some other function, but don't do it in
the fix patch itself that will be backported to stable releases.)

Patch 3/3 is the only patch that needs to be rebased, and seem to be the
patch that solves your issue.

I don't like the way that patch 3/3 is implemented.

ECAM will use two iATUs, one for PCIE_ATU_TYPE_CFG0 one for
PCIE_ATU_TYPE_CFG1. But this patch completely disregards that
this driver already reserves iATU index 0 for PCIE_ATU_TYPE_CFG0,
but for non-ECAM versions.

Now I understand why they have patch 1/3 in this series.

But it is still wrong. It has to change the indexing based on ECAM
is used or not.

Please try the attached patch on top of my series.

It avoids the need to introduce a new struct member.

Kind regards,
Niklas

View attachment "0001-PCI-dwc-Fix-ECAM.patch" of type "text/plain" (4400 bytes)