Re: [PATCH V2 00/23] MMCONFIG refactoring and support for ARM64 PCI hostbridge init based on ACPI

[Tomasz Nowicki]

On 21.12.2015 13:10, Lorenzo Pieralisi wrote:
> On Fri, Dec 18, 2015 at 06:56:39PM +0000, okaya@xxxxxxxxxxxxxx wrote:
>
> [...]
>
> > Here is what I have as an IO resource.
> >
> > 		QWORDIO(			//Consumed-And-produced resource
> > 			ResourceProducer,	// bit 0 of general flags is 0
> > 			MinFixed,		// Range is fixed
> > 			MaxFixed,		// Range is fixed
> > 			PosDecode,
> > 			EntireRange,
> > 			0x0000,			// Granularity
> > 			0x1000,		// Min, 0 is not accepted
> > 			0x10FFF,		// Max
> > 			0x8FFFFFEF000,	// Translation
> > 			0x10000,		// Range Length
> > 			,, PI00
> > 		 )
> >
> > I don't have any type specified.
> >
> > I agree with Lorenzo's assessment. The min and max values represent the
> > PCI IO bus addresses. The translation offset is added to these values to
> > figure out the CPU view of the PCI IO range.
> >
> > The endpoints BAR addresses are programmed with IO addresses ranging
> > between 0x1000 and 0x10FFF for this example above.
> >
> > Here is another question. Chris Covington and I asked this question on a
> > private email to you but we didn't hear back.
> >
> > We were referring to a Linaro IO hack patch as we were not sure whether
> > this was a limitation of the hack or a general expectation for ARM64 PCI
> > in general.
> >
> > I'll repeat it here.
> >
> > I have multiple root ports with the same IO port configuration in the
> > current ACPI table.
> >
> > Root port 0 = IO range 0x1000-0x10FFF
> > Root port 1 = IO range 0x1000-0x10FFF
> > Root port 2 = IO range 0x1000-0x10FFF
>
> It is fine. You end up mapping for each of those a 4k window of the
> virtual address space allocated to IO and that's what you will have in
> the kernel PCI resources (not in the HW BARs though). If that was a problem
> it would be even for the current DT host controllers eg:
>
> arch/arm64/boot/dts/apm/apm-storm.dtsi
>
> it should not be (again I will let Arnd comment on this since he may be
> aware of issues encountered on other arches/platforms).

Root port 0 = IO range 0x1000-0x10FFF
Root port 1 = IO range 0x1000-0x10FFF
Root port 2 = IO range 0x1000-0x10FFF

If above ranges are mapped into different CPU windows, then yes, it is fine.

Tomasz

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