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. > > This is not the problem of this patch set, but need updating > the core ACPI resource parsing code, I'm working on that. I'm > just wondering there is no special IO space on IA64, how this works > on IA64? There is special handling for IO port on IA64. IA64 io ports are actually memory-mapped, and there may be multiple 64K IO port spaces. For example, each PCI domain may have its own 64k memory-mapped IO space. Thanks! Gerry > > Thanks > Hanjun -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
