linux-kernel - Re: [PATCH V3 00/21] MMCONFIG refactoring and support for ARM64 PCI hostbridge init based on ACPI

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Date:	Thu, 14 Jan 2016 11:38:44 -0500
From:	Mark Salter <msalter@...hat.com>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Sinan Kaya <okaya@...eaurora.org>
Cc:	Tomasz Nowicki <tn@...ihalf.com>, bhelgaas@...gle.com,
	arnd@...db.de, will.deacon@....com, catalin.marinas@....com,
	rjw@...ysocki.net, hanjun.guo@...aro.org,
	jiang.liu@...ux.intel.com, Stefano.Stabellini@...citrix.com,
	robert.richter@...iumnetworks.com, mw@...ihalf.com,
	Liviu.Dudau@....com, ddaney@...iumnetworks.com, tglx@...utronix.de,
	wangyijing@...wei.com, Suravee.Suthikulpanit@....com,
	linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linaro-acpi@...ts.linaro.org, jchandra@...adcom.com, jcm@...hat.com
Subject: Re: [PATCH V3 00/21] MMCONFIG refactoring and support for ARM64 PCI
 hostbridge init based on ACPI

On Thu, 2016-01-14 at 16:12 +0000, Lorenzo Pieralisi wrote:
> On Thu, Jan 14, 2016 at 10:38:19AM -0500, Sinan Kaya wrote:
> > On 1/14/2016 10:29 AM, Mark Salter wrote:
> > On Wed, 2016-01-13 at 14:20 +0100, Tomasz Nowicki wrote:
> > > IO resources on Mustang get disabled unless I do:
> > > 
> > > @@ -126,9 +126,10 @@ static void acpi_dev_ioresource_flags(struct
> > > resource *res, u64 len, if (!acpi_dev_resource_len_valid(res->start,
> > > res->end, len, true)) res->flags |= IORESOURCE_DISABLED |
> > > IORESOURCE_UNSET;
> > > 
> > > +#if 0 if (res->end >= 0x10003) res->flags |= IORESOURCE_DISABLED |
> > > IORESOURCE_UNSET; - +#endif
> > > 
> > > res->end is way beyond 0x10003 on Mustang:
> > > 
> > > pci_bus 0000:00: root bus resource [io  0x0000-0xffff window] (bus
> > > address [0x10000000-0x1000ffff])
> > > 
> > > 
> > 
> > Join the club. I complained about this and I got the message that we
> > just do what Intel does.  See Arnd Bergmann's reply.
> > 
> > [PATCH V2 00/23] MMCONFIG refactoring and support for ARM64 PCI
> > hostbridge init based on ACPI
> > 
> > 1/12/2016 9:30 AM
> > 
> > It is an artificial limit coming from the x86 world introduced into
> > common code.
> 
> Guys, I think you are mixing things up here, we discussed this to
> death, read the archives please.
> 
> The ACPI IO descriptors AddressMinimum/AddressMaximum describe
> the IO space PCI bus addresses. The AddressTranslation field
> provides the PCI IO space -> CPU physical address translation, or
> put it differently, the secondary to primary bus translation in
> ACPI jargon, that's how ACPI tables must be written for IO space,
> at least that's what IA64 does (and on ia64 IO space is memory
> mapped, as on arm64).
> 
> I bet APM IO descriptors specify the *CPU* physical address in
> the AddressMinimum field, and that's where the problem lies.
> 

You would lose that bet. AddressMinimum/Maximum describe the
PCI bus addresses.

                QWordIO (ResourceProducer, MinFixed, MaxFixed, PosDecode, EntireRange,
                    0x0000000000000000, // Granularity
                    0x0000000010000000, // Range Minimum
                    0x000000001000FFFF, // Range Maximum
                    0x000000E000000000, // Translation Offset
                    0x0000000000010000, // Length
                    ,, , TypeStatic)


> Jiang's patch:
> 
> https://lkml.org/lkml/2015/12/16/249
> 
> parses the IO descriptors and stores the AddressMinimum, AddressMaximum
> in the IO resource (with AddressTranslation as offset which must be the
> *CPU* physical address mapping IO), from the log above it seems to me in
> AddressMinimum APM specifies the *CPU* physical address generating IO
> cycles.
> 
> All in all, I was right to fear this would happen, and I already
> raised the point within the ACPI spec working group, ACPI IO
> descriptors specification is ambiguous and we must agree on how
> they have to be specified once for all.
> 
> Lorenzo