quoted

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.

quoted

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

quoted

Thanks!
Yijing.

quoted

Best regards,
Liviu

quoted

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.

quoted

quoted

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

quoted

Rob

-- 
Thanks!
Yijing

-- 
Thanks!
Yijing

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Thanks!
Yijing