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Date: Fri, 6 Nov 2015 23:44:21 +0800 From: Jiang Liu <jiang.liu@...ux.intel.com> To: Lorenzo Pieralisi <lorenzo.pieralisi@....com> Cc: Tomasz Nowicki <tn@...ihalf.com>, Bjorn Helgaas <bhelgaas@...gle.com>, "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>, Marc Zyngier <marc.zyngier@....com>, Hanjun Guo <hanjun.guo@...aro.org>, Liviu Dudau <Liviu.Dudau@....com>, linux-acpi@...r.kernel.org, linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org Subject: Re: [Patch v7 4/7] PCI/ACPI: Add interface acpi_pci_root_create() On 2015/11/6 23:32, Jiang Liu wrote: > On 2015/11/6 22:45, Lorenzo Pieralisi wrote: >> On Fri, Nov 06, 2015 at 09:22:46PM +0800, Jiang Liu wrote: >>> On 2015/11/6 20:40, Tomasz Nowicki wrote: >>>> On 06.11.2015 12:46, Jiang Liu wrote: >>>>> On 2015/11/6 18:37, Tomasz Nowicki wrote: >>>>>> On 06.11.2015 09:52, Jiang Liu wrote: >>>>>> Sure, ARM64 (0-16M IO space) QEMU example: >>>>>> DWordIO (ResourceProducer, MinFixed, MaxFixed, PosDecode, EntireRange, >>>>>> 0x00000000, // Granularity >>>>>> 0x00000000, // Range Minimum >>>>>> 0x0000FFFF, // Range Maximum >>>>>> 0x3EFF0000, // Translation Offset >>>>>> 0x00010000, // Length >>>>>> ,, , TypeStatic) >>>>> The above DWordIO resource descriptor doesn't confirm to the ACPI spec. >>>>> According to my understanding, ARM/ARM64 has no concept of IO port >>>>> address space, so the PCI host bridge will map IO port on PCI side >>>>> onto MMIO on host side. In other words, PCI host bridge on ARM64 >>>>> implement a IO Port->MMIO translation instead of a IO Port->IO Port >>>>> translation. If that's true, it should use 'TypeTranslation' instead >>>>> of 'TypeStatic'. And kernel ACPI resource parsing interface doesn't >>>>> support 'TypeTranslation' yet, so we need to find a solution for it. >>>> >>>> I think you are right, we need TypeTranslation flag for ARM64 DWordIO >>>> descriptors and an extra kernel patch to support it. >>> How about the attached to patch to support TypeTranslation? >>> It only passes compilation:) >> >> Eh, hopefully there are not any ACPI tables out there with that bit >> set that work _today_ and would not work with the patch attached :) >> >> My question is still there: do we want to handle the same problem >> as ia64 has in a different manner ? Certainly we won't be able >> to update ia64 platforms ACPI tables, so we would end up with >> two platforms handling IO resources in different ways unless I am >> missing something here. > There are some difference between IA64 and ARM64. > On IA64, it supports 16M IO address space per PCI domain and 256 PCI > domains at max. So the system IO address space is 16M * 256 = 4G. > So it does two level translations to support IO port > 1) translate PCI bus local IO port address into system global IO port > address by adding acpi_des->translation_offset. > 2) translate the 4G system IO port address space into MMIO address. > IA64 has reserved a 4G space for IO port mapping. This translation > is done by arch specific method. > In other word, IA64 needs two level translation, but ACPI only provides > on (trans_type, trans_offset) pair for encoding, so it's used for step 1). > > For ARM64, I think currently it only needs step 2). > >> >> BTW, why would we add offset to res->start only if TypeTranslation is >> clear ? Is not that something we would do just to make things "work" ? >> That flag has no bearing on the offset, only on the resource type AFAIK. > It's not a hack, but a way to interpret ACPI spec:) > > With current linux resource management framework, we need to allocate > both MMIO and IO port address space range for an ACPI resource of type > 'TypeTranslation'. And struct resource could be either IO port or MMIO, > not both. So the choice is to keep the resource as IO port, and let > arch code to build the special MMIO mapping for it. Otherwise it will > break too many things if we convert the resource as MMIO. > > That said, we need to add translation_offset to convert bus local > IO port address into system global IO port address if it's type of > TypeStatic, because ioresource_ioport uses system global IO port > address. > > For an ACPI resource of type TypeTranslation, system global IO port > address equals bus local IO port address, and the translation_offset > is used to translate IO port address into MMIO address, so we shouldn't > add translation_offset to the IO port resource descriptor. One note for the TypeTranslation case, the arch code needs to reset resource_win->offset to zero after setting up the MMIO map. Sample code as below: va = ioremap(resource_win->offset + res->start, resource_size(res)); resource_win->offset = 0; Otherwise it will break pcibios_resource_to_bus() etc. > > Thanks, > Gerry > >> >> This without taking into account ARM64 systems shipping with ACPI >> tables that does not set the TypeTranslation at present. >> >> On top of that, I noticed that core ACPI code handles Sparse >> Translation (ie _TRS), that should be considered meaningful only if _TTP >> is set (and that's not checked). > Yes, that's a flaw:( > >> >> Thoughts ? >> >> Thanks, >> Lorenzo >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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