RFC: replace device_type with new "class" property?

[Yoder Stuart-B08248]

> -----Original Message-----
> From: Wood Scott-B07421 
> Sent: Tuesday, October 30, 2007 11:34 AM
> To: Yoder Stuart-B08248
> Cc: David Gibson; Olof Johansson; linuxppc-dev at ozlabs.org
> Subject: Re: RFC: replace device_type with new "class" property?
> 
> On Tue, Oct 30, 2007 at 09:23:14AM -0700, Yoder Stuart-B08248 wrote:
> >   mpic: pic at 40000 {
> >      clock-frequency = <0>;
> >      interrupt-controller;
> >      #address-cells = <0>;
> >      #interrupt-cells = <2>;
> >      reg = <40000 40000>;
> >      compatible = "fsl,xyz";
> >      big-endian;
> > }
> > 
> > Note-- I removed the device_type property and changed
> > compatible somewhat.  How are you going to find where
> > the meaning interrupt controller's interrupt cells are
> > defined?   What spec will you look at?
> 
> The binding for fsl,xyz.

Not every string listed in compatible has a spec 
backing it (or should be required to).  You would
have to go look at the source code and cross your
fingers that the comments were sufficient.

Another good reason for device_type-- it helps 
distinguish between two similar classes of devices.
Both "open-pic" and "isa-pic" look very similar but
have different encodings of their interrupt cells.
Without a device_type it may be difficult or impossible
to distinguish them unless the "name" and
"compatible" are luckily clear enough.

Stuart