From: wangyijing@huawei•com (Yijing Wang)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v10 07/10] OF: Introduce helper function for getting PCI domain_nr
Date: Wed, 10 Sep 2014 09:44:51 +0800 [thread overview]
Message-ID: <540FAD13.9030502@huawei.com> (raw)
In-Reply-To: <20140909141122.GY27864@e106497-lin.cambridge.arm.com>
>> OK. Sorry, I have one last question, because domain will be used to calculate the address used to
>> access PCI hardware config registers. So if DTS file doesn't report the domain, how do we know
>> we would access the right registers when we use the auto increment domain vaule ?
>
> That's a good question and sides with Arnd's suggestion to try to mandate the presence of the PCI
> domain in the DTS. However, by grepping through the source code, it looks like the architectures
> that use the domain number for reading config registers (x86-based) are non-DT architectures,
> while DT-aware arches seem to ignore the domain number except when printing out messages. Is that
> another confirmation that most DT-aware architectures have only run with domain_nr = 0?
>
Arnd's suggestion is make sense to me, thanks for Bjorn's detailed explanation, now I know domain_nr
is purely internal to kernel in DT-aware platform, it's not needed when access PCI config space.
Thanks!
Yijing.
>
>> Has there a mechanism to make sure system can access the correct registers by the domain ?
>
> Not as such if you look with x86 glasses. With the exception of powerpc all other architecures
> seem to happily assume domain_nr = 0 and ignore it in the computation of configuration registers
> offsets.
>
> Best regards,
> Liviu
>
>>
>> Thanks!
>> Yijing.
>>
>>>
>>> Best regards,
>>> Liviu
>>>
>>>>
>>>> PCI get domain by ACPI "_SEG" in IA64(drivers/acpi/pci_root.c)
>>>> ......
>>>> status = acpi_evaluate_integer(handle, METHOD_NAME__SEG, NULL,
>>>> &segment);
>>>> if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
>>>> dev_err(&device->dev, "can't evaluate _SEG\n");
>>>> result = -ENODEV;
>>>> goto end;
>>>> }
>>>> .......
>>>>
>>>> Thanks!
>>>> Yijing.
>>>>
>>>>>
>>>>>> This function
>>>>>> is just a weird mixture of data retrieval and allocation. I think you
>>>>>> need to separate it into 2 functions.
>>>>>
>>>>> It is meant to do allocation with the retrieval being a short-cut (or fine
>>>>> control if you want).
>>>>>
>>>>> I need to think a bit more for a better solution.
>>>>>
>>>>> Best regards,
>>>>> Liviu
>>>>>
>>>>>>
>>>>>> Rob
>>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Thanks!
>>>> Yijing
>>>>
>>>>
>>>
>>
>>
>> --
>> Thanks!
>> Yijing
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
>> the body of a message to majordomo at vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
>
--
Thanks!
Yijing
next prev parent reply other threads:[~2014-09-10 1:44 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-08 13:54 [PATCH v10 00/10] Support for creating generic PCI host bridges from DT Liviu Dudau
2014-09-08 13:54 ` [PATCH v10 01/10] Fix ioport_map() for !CONFIG_GENERIC_IOMAP cases Liviu Dudau
2014-09-08 13:54 ` [PATCH v10 02/10] PCI: Introduce helper functions to deal with PCI I/O ranges Liviu Dudau
2014-09-08 13:54 ` [PATCH v10 03/10] ARM: Define PCI_IOBASE as the base of virtual PCI IO space Liviu Dudau
2014-09-08 13:54 ` [PATCH v10 04/10] PCI: OF: Fix the conversion of IO ranges into IO resources Liviu Dudau
2014-09-08 13:54 ` [PATCH v10 05/10] PCI: Create pci_host_bridge before its associated bus in pci_create_root_bus Liviu Dudau
2014-09-08 13:54 ` [PATCH v10 06/10] PCI: Introduce generic domain handling for PCI busses Liviu Dudau
2014-09-08 14:03 ` Catalin Marinas
2014-09-08 14:05 ` Liviu Dudau
2014-09-08 13:54 ` [PATCH v10 07/10] OF: Introduce helper function for getting PCI domain_nr Liviu Dudau
2014-09-08 14:27 ` Rob Herring
2014-09-08 14:54 ` Liviu Dudau
2014-09-08 15:27 ` Rob Herring
2014-09-08 15:59 ` Liviu Dudau
2014-09-08 16:39 ` Jason Gunthorpe
2014-09-09 5:54 ` Yijing Wang
2014-09-09 8:46 ` Liviu Dudau
2014-09-09 9:16 ` Arnd Bergmann
2014-09-09 11:20 ` Catalin Marinas
2014-09-10 18:19 ` Arnd Bergmann
2014-09-11 14:11 ` Phil Edworthy
2014-09-11 14:49 ` Arnd Bergmann
2014-09-09 14:17 ` Bjorn Helgaas
2014-09-09 9:30 ` Yijing Wang
2014-09-09 14:11 ` Liviu Dudau
2014-09-10 1:44 ` Yijing Wang [this message]
2014-09-09 14:26 ` Bjorn Helgaas
2014-09-09 15:41 ` Jason Gunthorpe
2014-09-10 2:44 ` Rob Herring
2014-09-10 16:32 ` Jason Gunthorpe
2014-09-10 1:55 ` Yijing Wang
2014-09-10 13:04 ` Liviu Dudau
2014-09-08 13:54 ` [PATCH v10 08/10] OF: PCI: Add support for parsing PCI host bridge resources from DT Liviu Dudau
2014-09-09 13:35 ` Lorenzo Pieralisi
2014-09-10 14:22 ` Liviu Dudau
2014-09-10 15:10 ` Lorenzo Pieralisi
2014-09-10 15:32 ` Liviu Dudau
2014-09-10 16:37 ` Lorenzo Pieralisi
2014-09-10 16:53 ` Liviu Dudau
2014-09-10 17:06 ` Lorenzo Pieralisi
2014-09-08 13:54 ` [PATCH v10 09/10] PCI: Assign unassigned bus resources in pci_scan_root_bus() Liviu Dudau
2014-09-12 10:13 ` Suravee Suthikulpanit
2014-09-12 10:34 ` Liviu Dudau
2014-09-08 13:54 ` [PATCH v10 10/10] PCI: Introduce pci_remap_iospace() for remapping PCI I/O bus resources into CPU space Liviu Dudau
2014-09-08 16:07 ` [PATCH v10 00/10] Support for creating generic PCI host bridges from DT Liviu Dudau
2014-09-12 8:25 ` Suravee Suthikulpanit
2014-09-12 9:30 ` Liviu Dudau
2014-09-12 10:00 ` Suravee Suthikulpanit
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=540FAD13.9030502@huawei.com \
--to=wangyijing@huawei$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox