On Thu, 2015-06-04 at 14:41 +0800, Jiang Liu wrote: > On 2015/6/4 14:31, Hanjun Guo wrote: > > Hi Jiang, > > > > On 2015年06月04日 09:54, Jiang Liu wrote: > >> On 2015/6/4 4:27, Al Stone wrote: > >>> On 06/02/2015 12:12 AM, Jiang Liu wrote: > >>>> This patch set consolidates common code to support ACPI PCI root on x86 > >>>> and IA64 platforms into ACPI core, to reproduce duplicated code and > >>>> simplify maintenance. And a patch set based on this to support ACPI > >>>> based > >>>> PCIe host bridge on ARM64 has been posted at: > >>> > >>> Link is missing (or it's a typo of some flavor). > >> HI Al, > >> Sorry, I missed the link. It has been posted at: > >> https://lkml.org/lkml/2015/5/26/207 > > > > I failed to get io resources for PCI hostbridge when I was testing PCI > > on ARM64 QEMU, I debugged this for quite a while, and finally found out > > that ACPI resource parsing for IO is not suitable for ARM64, because io > > space for x86 is 64K, but 16M for ARM64. > > > > This issue is only found when the firmware representing the io resource > > using the type ACPI_RESOURCE_TYPE_ADDRESS32, so the io address will > > greater than 64k. > > > > In drivers/acpi/resource.c: > > > > static void acpi_dev_ioresource_flags(struct resource *res, u64 len, > > u8 io_decode, u8 translation_type) > > { > > res->flags = IORESOURCE_IO; > > > > [...] > > > > if (res->end >= 0x10003) > > res->flags |= IORESOURCE_DISABLED | IORESOURCE_UNSET; > > > > [...] > > } > > > > so the code will filter out res->end >= 0x10003, and in my case, it will > > more than 64K, so we can't get the IO resources. > > > > I got a question, why we use if (res->end >= 0x10003) here? > > I mean 64k will be 0x10000, and in that case, we should use > > if (res->end >= 0x10000) here, not 0x10003, any history behind that? > > Hi Hanjun, > This is a special tricky for x86. You may read a dword(four bytes) from > IO port 0xffff, so the effective io port space is 0x10003 bytes. > Is there something in ACPI spec which would limit PCI IO space to 64K? PCI itself allows 32-bit IO addresses and at least some arm64 platforms use PCI bus addresses above 64K for IO transactions. From a PCI view, the (res->end >= 0x10003) check doesn't make sense. Am I missing something? -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
