linux-kernel - Re: [PATCH V7 07/11] pci, acpi: Handle ACPI companion assignment.

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Date:	Fri, 13 May 2016 11:32:50 +0100
From:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
Cc:	Jayachandran C <jchandra@...adcom.com>,
	Bjorn Helgaas <helgaas@...nel.org>,
	Tomasz Nowicki <tn@...ihalf.com>,
	Arnd Bergmann <arnd@...db.de>,
	Will Deacon <will.deacon@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Hanjun Guo <hanjun.guo@...aro.org>,
	Sinan Kaya <okaya@...eaurora.org>,
	robert.richter@...iumnetworks.com, Marcin Wojtas <mw@...ihalf.com>,
	Liviu.Dudau@....com, David Daney <ddaney@...iumnetworks.com>,
	Wangyijing <wangyijing@...wei.com>,
	Suravee Suthikulanit <Suravee.Suthikulpanit@....com>,
	Mark Salter <msalter@...hat.com>,
	Linux PCI <linux-pci@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
	Jon Masters <jcm@...hat.com>,
	Andrea Gallo <andrea.gallo@...aro.org>,
	Duc Dang <dhdang@....com>, jeremy.linton@....com,
	liudongdong3@...wei.com, Christopher Covington <cov@...eaurora.org>
Subject: Re: [PATCH V7 07/11] pci, acpi: Handle ACPI companion assignment.

On Thu, May 12, 2016 at 01:27:23PM +0200, Rafael J. Wysocki wrote:
> On Thu, May 12, 2016 at 12:43 PM, Jayachandran C <jchandra@...adcom.com> wrote:
> > On Thu, May 12, 2016 at 4:13 AM, Bjorn Helgaas <helgaas@...nel.org> wrote:
> >> On Wed, May 11, 2016 at 10:30:51PM +0200, Rafael J. Wysocki wrote:
> >>> On Wed, May 11, 2016 at 12:11 PM, Lorenzo Pieralisi
> >>> <lorenzo.pieralisi@....com> wrote:
> >>> > On Tue, May 10, 2016 at 08:37:00PM +0200, Rafael J. Wysocki wrote:
> >>> >> On Tue, May 10, 2016 at 5:19 PM, Tomasz Nowicki <tn@...ihalf.com> wrote:
> 
> [cut]
> 
> >
> > If we are moving the ACPI/PCI code from drivers/acpi to
> > arch/arm64/ , there is an issue in having the header file
> > ecam.h in drivers/pci
> >
> > The current include of "../pci/ecam.h" is slightly ugly (Arnd
> > and David had already noted this), but including the driver
> > header from arch code would be even worse.
> >
> > I can either merge ecam.h into include/linux/pci.h
> > or move it to a new file include/linux/pci-ecam.h, any
> > suggestion on which is preferable?
> 
> My preference would be pci-ecam.h as we did a similar thing for
> pci-dma.h, for example, but basically this is up to Bjorn.

A word of caution for all interested parties, what we may move
to arch/arm64 (if Catalin and Will are ok with that) here is content
of drivers/acpi/pci_root_generic.c, not drivers/acpi/pci_mcfg.c (and
definitely not the MCFG quirks handling that is coming up next on top
of this series).

I just wanted to make sure we understand that MCFG quirks handling
like eg:

https://lkml.org/lkml/2016/4/28/790

that is coming up following this series has no chance whatsoever to
be handled within arch/arm64, it is just not going to happen.

Maybe I am jumping the gun, I just want to make sure that everyone is
aware that moving part of this series to arch/arm64 has implications,
(and that's why I said that moving part of this code to arch/arm64 is
not as simple as it looks) it may be ok to have an ACPI PCI
implementation that is arch/arm64 specific (mostly for IO space and PCI
resources assignment handling that unfortunately is not uniform across
X86, IA64 and ARM64), but MCFG quirks and related platform code stay out
of arch/arm64 I guess we are all aware of that, just wanted to make
sure :)

Lorenzo