linux-kernel - Re: [PATCH 05/11] x86, pci, acpi: Move arch-agnostic MMCONFIG (aka ECAM) and ACPI code out of arch/x86/ directory

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Message-ID: <561FB985.8070509@linaro.org>
Date:	Thu, 15 Oct 2015 16:34:45 +0200
From:	Tomasz Nowicki <tomasz.nowicki@...aro.org>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"hanjun.guo@...aro.org" <hanjun.guo@...aro.org>,
	Liviu Dudau <Liviu.Dudau@....com>,
	Yijing Wang <wangyijing@...wei.com>,
	Will Deacon <Will.Deacon@....com>,
	Arnd Bergmann <arnd@...db.de>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
	"msalter@...hat.com" <msalter@...hat.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>
Subject: Re: [PATCH 05/11] x86, pci, acpi: Move arch-agnostic MMCONFIG (aka
 ECAM) and ACPI code out of arch/x86/ directory

On 15.10.2015 15:22, Lorenzo Pieralisi wrote:
> On Mon, Sep 14, 2015 at 03:55:50PM +0100, Tomasz Nowicki wrote:
>
> [...]
>
>>> Well, I still have not figured out whether on arm64 the raw accessors
>>> required by ACPICA make sense.
>>>
>>> So either arm64 relies on the generic MCFG based raw read and writes
>>> or we define the global raw read and writes as empty (ie x86 overrides
>>> them anyway).
>>>
>>
>> My concerns/ideas related to raw accessors for ARM64, please correct me
>> at any point.
>>
>> ACPI spec - chapter: 19.5.96 OperationRegion (Declare Operation Region)
>> defines PCI_Config as one of region types. Every time ASL opcode
>> operates on corresponding PCI config space region, ASL interpreter is
>> dispatching address space to our raw accessors, please see
>> acpi_ex_pci_config_space_handler, acpi_ev_pci_config_region_setup calls.
>> What is more important, such operations may happen after (yes after) bus
>> enumeration, but always raw accessors are called at the end with the
>> {segment, bus, dev, fn} tuple.
>>
>> Giving above, here are some ideas:
>> 1. We force somehow vendors to avoid operations on PCI config regions in
>> ASL code. PCI config region definitions still fall into Hardware Reduced
>> profile, so new ACPICA special subset for ARM64 is need. Then raw ACPI
>> accessors can be empty (and overridden by x86).
>
> I am coming back to this, I am not sure that PCI config based OperationRegions
> fall into Hardware Reduced profile, I will finally start a thread on ASWG
> to check that.
>
> Other than that, are you posting an updated version of this series soon ?
> Let me know if you need help refactoring/testing the patches.
>

I am planing to send updated version next week, but honestly next 
version does make sense if we figure out raw accessors issue. So I will 
clean up all around meanwhile and optionally raw accessor.

Of course your help in testing is welcomed. Also please have a look at 
my GICv3/ITS patches, they are important for ACPI PCI.

Regards,
Tomasz
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