Messages in this thread | | | Date | Wed, 10 Sep 2014 09:55:48 +0800 | From | Yijing Wang <> | Subject | Re: [PATCH v10 07/10] OF: Introduce helper function for getting PCI domain_nr |
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>> 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 ? >> Has there a mechanism to make sure system can access the correct registers by the domain ? > > I think you're referring to config access via ECAM (PCIe r3.0, sec > 7.2.2). In that case, I don't think the domain should be used to > compute the memory-mapped configuration address. Each host bridge is > in exactly one domain, and each host bridge has an associated ECAM > area base. The address calculation uses the bus number, device > number, function number, and register number to compute an offset into > the ECAM area. > > So as long as the DT tells you the ECAM information for each host > bridge, that should be sufficient. The domain number is then just a > Linux convenience and is not tied to the platform as it is on ia64.
Hi Bjorn, you are right, thanks for your detailed explanation! :)
Thanks! Yijing.
> > Bjorn > > . >
-- Thanks! Yijing
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