From: Hanjun Guo <hanjun.guo@linaro.org>
To: Jiang Liu <jiang.liu@linux.intel.com>, Al Stone <ahs3@redhat.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Bjorn Helgaas <bhelgaas@google.com>,
Marc Zyngier <marc.zyngier@arm.com>,
Liviu Dudau <Liviu.Dudau@arm.com>,
Yijing Wang <wangyijing@huawei.com>
Cc: Lv Zheng <lv.zheng@intel.com>,
"lenb @ kernel . org" <lenb@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org,
"x86 @ kernel . org" <x86@kernel.org>,
linux-arm-kernel@lists.infradead.org,
Mark Salter <msalter@redhat.com>
Subject: Re: [Patch v4 0/8] Consolidate ACPI PCI root common code into ACPI core
Date: Thu, 04 Jun 2015 15:02:56 +0800 [thread overview]
Message-ID: <556FF820.5070405@linaro.org> (raw)
In-Reply-To: <556FF32B.9010900@linux.intel.com>
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
next prev parent reply other threads:[~2015-06-04 7:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-02 6:12 [Patch v4 0/8] Consolidate ACPI PCI root common code into ACPI core Jiang Liu
2015-06-02 6:12 ` [Patch v4 1/8] ACPI/PCI: Enhance ACPI core to support sparse IO space Jiang Liu
2015-06-02 6:12 ` [Patch v4 2/8] ia64/PCI/ACPI: Use common ACPI resource parsing interface for host bridge Jiang Liu
2015-06-02 6:12 ` [Patch v4 3/8] ia64/PCI: Use common struct resource_entry to replace struct iospace_resource Jiang Liu
2015-06-02 6:12 ` [Patch v4 4/8] x86/PCI: Rename struct pci_sysdata as struct pci_controller Jiang Liu
2015-06-02 6:12 ` [Patch v4 5/8] ARM64/PCI/ACPI: Introduce struct pci_controller for ACPI Jiang Liu
2015-06-02 9:35 ` Lorenzo Pieralisi
2015-06-03 8:44 ` Hanjun Guo
2015-06-03 9:36 ` Jiang Liu
2015-06-03 10:03 ` Lorenzo Pieralisi
2015-06-03 10:21 ` Jiang Liu
2015-06-03 12:49 ` Lorenzo Pieralisi
2015-06-02 6:12 ` [Patch v4 6/8] PCI/ACPI: Consolidate common PCI host bridge code into ACPI core Jiang Liu
2015-06-02 6:12 ` [Patch v4 7/8] x86/PCI/ACPI: Use common interface to support PCI host bridge Jiang Liu
2015-06-02 6:12 ` [Patch v4 8/8] ia64/PCI/ACPI: " Jiang Liu
2015-06-02 6:46 ` [Patch v4 0/8] Consolidate ACPI PCI root common code into ACPI core Hanjun Guo
2015-06-03 20:27 ` Al Stone
2015-06-04 1:54 ` Jiang Liu
2015-06-04 6:31 ` Hanjun Guo
2015-06-04 6:41 ` Jiang Liu
2015-06-04 7:02 ` Hanjun Guo [this message]
2015-06-04 15:51 ` Mark Salter
2015-06-04 16:29 ` Jiang Liu
2015-06-04 16:57 ` Mark Salter
2015-06-08 3:59 ` Hanjun Guo
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