linux-kernel - Re: [PATCH v3 05/12] PCI: of_property: Assign PCI instead of CPU bus address to dynamic bridge nodes

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Message-ID: <20241104234937.GA1446920@bhelgaas>
Date: Mon, 4 Nov 2024 17:49:37 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Andrea della Porta <andrea.porta@...e.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczynski <kw@...ux.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Bartosz Golaszewski <brgl@...ev.pl>,
	Derek Kiernan <derek.kiernan@....com>,
	Dragan Cvetic <dragan.cvetic@....com>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Saravana Kannan <saravanak@...gle.com>, linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-gpio@...r.kernel.org,
	Masahiro Yamada <masahiroy@...nel.org>,
	Stefan Wahren <wahrenst@....net>,
	Herve Codina <herve.codina@...tlin.com>,
	Luca Ceresoli <luca.ceresoli@...tlin.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH v3 05/12] PCI: of_property: Assign PCI instead of CPU bus
 address to dynamic bridge nodes

On Mon, Nov 04, 2024 at 08:35:21PM +0530, Manivannan Sadhasivam wrote:
> On Mon, Nov 04, 2024 at 09:54:57AM +0100, Andrea della Porta wrote:
> > On 22:39 Sat 02 Nov     , Manivannan Sadhasivam wrote:
> > > On Mon, Oct 28, 2024 at 03:07:22PM +0100, Andrea della Porta wrote:
> > > > When populating "ranges" property for a PCI bridge, of_pci_prop_ranges()
> > > > incorrectly use the CPU bus address of the resource. Since this is a PCI-PCI
> > > > bridge, the window should instead be in PCI address space. Call
> > > > pci_bus_address() on the resource in order to obtain the PCI bus
> > > > address.
> > > 
> > > of_pci_prop_ranges() could be called for PCI devices also (not just PCI
> > > bridges), right?
> > 
> > Correct. Please note however that while the PCI-PCI bridge has the parent
> > address in CPU space, an endpoint device has it in PCI space: here we're
> > focusing on the bridge part. It probably used to work before since in many
> > cases the CPU and PCI address are the same, but it breaks down when they
> > differ.
> 
> When you say 'focusing', you are specifically referring to the
> bridge part of this API I believe. But I don't see a check for the
> bridge in your change, which is what concerning me. Am I missing
> something?

I think we want this change for all devices in the PCI address
domain, including PCI-PCI bridges and endpoints, don't we?  All those
"ranges" addresses should be in the PCI domain.

Bjorn