Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751404AbbFDHDR (ORCPT ); Thu, 4 Jun 2015 03:03:17 -0400 Received: from mail-pd0-f176.google.com ([209.85.192.176]:35202 "EHLO mail-pd0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750805AbbFDHDF (ORCPT ); Thu, 4 Jun 2015 03:03:05 -0400 Message-ID: <556FF820.5070405@linaro.org> Date: Thu, 04 Jun 2015 15:02:56 +0800 From: Hanjun Guo User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Jiang Liu , Al Stone , "Rafael J . Wysocki" , Bjorn Helgaas , Marc Zyngier , Liviu Dudau , Yijing Wang CC: Lv Zheng , "lenb @ kernel . org" , LKML , linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, "x86 @ kernel . org" , linux-arm-kernel@lists.infradead.org, Mark Salter Subject: Re: [Patch v4 0/8] Consolidate ACPI PCI root common code into ACPI core References: <1433225576-8215-1-git-send-email-jiang.liu@linux.intel.com> <556F6332.2040501@redhat.com> <556FAFEF.6040802@linux.intel.com> <556FF0AD.6000901@linaro.org> <556FF32B.9010900@linux.intel.com> In-Reply-To: <556FF32B.9010900@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2954 Lines: 78 On 2015年06月04日 14:41, 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. Thanks for the explanation, how about add a patch to comment on it? if it's ok to you and will improve the code readability, I can prepare one. > >> >> 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. That's the case for ARM64 too, I will review the IA64 code for reference, great thanks for the help and explanation :) Thanks Hanjun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/