Subject: Re: [RFC] Device tree for new desktop platform in arch/powerpc

From: Benjamin Herrenschmidt <[email-masked]>
Date: Thu, 21 Jun 2007 22:36:46 +1000

> 2. I tried to define all ISA devices, which are integrated in the
> southbridge (VT82C686B). Currently these are child nodes of the device
> tree root. Should they be child nodes of the southbridge's PCI-to-ISA
> device node? If so, where should I specify the register address ranges
> (reg property)? In the PCI device node or in the ISA device nodes, as
> it is now?

You should have /pci/isa <--- this is the PCI2ISA bridge

and the ISA devices below that. Best is I send you an example of a CHRP
or pSeries devie-tree with ISA stuff on it tomorrow. Ping me if I
forget.

> 3. The dts files define the device_type of a serial port as "serial",
> whereas the OF spec says "pnpPNP,501". What's the difference between
> the two?

Use the pnp stuff for "compatible", you can mostly ignore device_type or
set it to the same as name.

> 4. I couldn't find any information for a device tree representation of
> the i8259 interrupt controller in the booting-without-of.txt file. Is
> my implementation correct (inspired by the OF documents)?

Haven't looked at your .dts yet but it should be "interrupt-controller",
compatible "chrp,iic" or "i8259", with a #interrupt-cells of 2 and
interrupts following the standard ISA encoding. You probably also want
an interrupt-parent property in the isa bridge node pointing back to the
8259 so it becomes the default for all ISA devices.

> I would be grateful, if you could take a look at my dts file and
> comment on every line that doesn't meet your views.

Will do as soon as I find some time...

Ben.