Subject: Re: [RFC] AmigaOne device tree source v2

From: "Gerhard Pircher" <[email-masked]>
Date: Tue, 04 Sep 2007 14:20:40 +0200

-------- Original-Nachricht --------
> Datum: Tue, 4 Sep 2007 00:52:02 +0200
> Von: Segher Boessenkool <[email-masked]>
> An: "Gerhard Pircher" <[email-masked]>
> CC: [email-masked], David Gibson <[email-masked]>
> Betreff: Re: [RFC] AmigaOne device tree source v2

> >>> Yeah, PCI is a special case for Linux.  Maybe add a "pciclass,XXXX"
> >>> compatible property though, for good measure.  Anything else isn't
> >>> all that useful I think.
> > Wouldn't that be the same as the class-code property?
> 
> Sure, except it is a different property.  If you use the "class-code"
> thing, you really should implement _all_ of the PCI binding's required
> properties.  If you don't (since Linux doesn't use it anyway), it might
> still be nice to have a "compatible" property at least (since that is
> what is used for figuring out what device driver to use for this device
> node).  Linux doesn't currently use that either, so you don't have to,
> but you could put it there and it would make sense, that's all.
Okay, I'll add a compatible = "pciclass,0101"; property to the node.
BTW: It looks like the Pegasos II device tree defines device_type = "spi"
for the IDE controller. Is that correct?

> If those addresses really show up in the PCI BARs (most controllers
> don't do that in legacy mode), the kernel's own PCI probing will
> see it already; if they aren't in BARs, it is a bit tricky to encode
> that correctly in the "reg" (it's perfectly well-defined, just a bit
> hard to get it right).
These addresses show up in the PCI BARs of the VIA 686B IDE controller,
even if it is configured for compatible mode.

> There is no such thing as "interrupt 14 and 15" on PCI.  You can use
> the interrupt mapping recommended practice to show two interrupts
> (and their polarity, and how they are routed to the relevant interrupt
> controller) in the IDE node.
But I'll still need a quirk in the IDE driver, because it doesn't make
use of any interrupt routing information in the device tree. If so, I
can omit the whole IDE controller device node and simply rely on the
IDE driver's probe functions and the Pegasos IDE IRQ quirk.
I wonder how this issue will be handled for libata and the via-pata
driver, since IIRC this one doesn't contain the Pegasos IDE IRQ quirk.

Thanks,

Gerhard

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