>> 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
>>
>> --
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>>
>
--
Thanks!
Yijing
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