RFC: new device types in the device tree (RE: [PATCH] powerpc: Add EDAC platform devices for 85xx)

[Yoder Stuart-B08248]

> -----Original Message-----
> From: linuxppc-dev-bounces+b08248=freescale.com at ozlabs.org 
> [mailto:linuxppc-dev-bounces+b08248=freescale.com at ozlabs.org] 
> On Behalf Of Segher Boessenkool
> Sent: Thursday, April 26, 2007 1:57 PM
> To: Dave Jiang
> Cc: linuxppc-dev at ozlabs.org; david at gibson.dropbear.id.au; 
> bluesmoke-devel at lists.sourceforge.net
> Subject: Re: [PATCH] powerpc: Add EDAC platform devices for 85xx
> 
> >>> +		mem-ctrl at 2000 {
> >>> +			device_type = "mem-ctrl";
> >>> +			compatible = "85xx";
> >>>
> >> I'm concerned this is too generic.
> >>
> > I'm supposing not all 85xx uses the same soc? Is there 
> something more
> > appropriate you can suggest? Thx!
> 
> "name" = "memory-controller"
> "compatible" = "fsl,85xx-memory-controller"
> (or a more specific 85xx model if the controller
> isn't identical across those chips)
> No "device_type" at all, since there is no binding
> for this kind of device.

Is "no device_type" really the approach that should be
taken?  

booting-without-of.txt currently reads:

   Every node which actually represents an actual device
   (that is, a node which isn't only a virtual "container"
   for more nodes, like "/cpus" is) is also required to
   have a "device_type" property indicating the type of
   node

The 1275 spec is 'Open Firmware centric' in that it says
you don't need a device_type if the node is not used
by Open Firmware.

What should the approach be for new device types that
keep popping up?   If the device type is generally useful
I think it makes sense to create a binding and add it to
booting-without-of.txt-- essentially documenting the
required properties, their values, and what they mean.

If it is vendor specific, that vendor should create some
vendors specific doc for their bindings--
Documentation/powerpc/fsl-of-dev-bindings.txt.

Comments?

Thanks,
Stuart Yoder