-------- Original-Nachricht -------- > Datum: Wed, 5 Sep 2007 12:48:05 +1000 > Von: David Gibson <[EMAIL PROTECTED]> > An: Gerhard Pircher <[EMAIL PROTECTED]> > CC: Segher Boessenkool <[EMAIL PROTECTED]>, linuxppc-dev@ozlabs.org > Betreff: Re: [RFC] AmigaOne device tree source v2
> That looks totally bogus. Unlike Segher, I think there are a few > cases where overlapping reg and ranges can make sense (PCI bridges > where config space is accessed indirectly via MMIO registers which lie > in the legacy ISA IO space is an example). But this doesn't look like > such a case - it just looks like whoever did the device tree > misunderstood the distinction between reg and ranges. AmigaOne's PCI bridge implements PCI config with indirect addressing, but not within the ISA I/O space. I just wanted to clear up the meaning of this reg entry, because it looks like everyone interprets the OF spec a little bit differently. > > > PCI legacy I/O is not direct mapped: there is no legacy I/O on a > > > PowerPC system bus. So, it can not be mentioned in the "ranges" > > > property, but the PHB registers used to access it should be shown > > > in the "reg" property. It could be a simple linear window (it > > > sounds like it is here?), but it could for example also be > > > implemented via an address/data register pair. > > Err... huh? The legacy IO space is assigned a block of addresses in > 3-word "OF-PCI-space by the PCI binding. When that is translated into > an MMIO range by the bridge, there's no reason that can't be encoded > into the ranges property. I defined the legacy I/O space together with the PCI I/O space in the ranges property of the PCI node: ranges = <01000000 0 00000000 fe000000 0 00c00000 The first 64k of this address space are mapped to ISA I/O in the PCI2ISA bridge node. > The whole damn point of the device tree is to avoid using this kind of > non-local information "I know what the board type is over there, so it > must be this PCI bridge over here". The node should have a compatible > property which is sufficient to select the right bridge driver. Yeah, I defined a compatible = "mai,articias"; property in the pci node. Are there any naming conventions (maybe lower case only)? > I think this is typically badly done at the moment, simply because PCI > has historically been set up by the platform code, rather than by a > "host bridge driver" in the mould of other drivers. I don't see that > changing real soon, but that doesn't mean we shouldn't at least put > enough information in the device tree to make it possible. I agree (even if it means more work for me :-) I'll post a revised version of the device tree. Thanks! Gerhard -- GMX FreeMail: 1 GB Postfach, 5 E-Mail-Adressen, 10 Free SMS. Alle Infos und kostenlose Anmeldung: http://www.gmx.net/de/go/freemail _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
