Subject: Re: [PATCH v2 6/7] Holly DTS

From: Segher Boessenkool <[email-masked]>
Date: Sat, 5 May 2007 22:44:12 +0200

>>> +/ {
>>> +	model = "ppc750-tsi109";
>>
>> "model" should be something really specific; typically
>> a (unique!) model number.  This means you can't use the
>> same device tree for Holly and Hickory (but there are
>> more reasons for that; see below).
>>
>>> +	compatible = "ppc750-tsi";
>>
>> The needs to be more specific as well; "ibm,holly"
>> or something.
>
> Why?  Holly and Hickory share the same memory map and devices.  The 
> only
> thing that differs from what I can tell is the actual CPU itself.

And the model number I suspect.

"ppc750-tsi" really isn't good enough as a "compatible"
property, there are many many more boards with some 750
and some TSI bridge.

>>> +  	tsi109@c0000000 {
>>> +		device_type = "tsi-bridge";
>>
>> Don't put a "device_type" here, it is useless
>> (and undefined).  There are more like this, but
>> perhaps Linux (wrongly) probes on "device_type"
>> for those, so the kernel would need updating
>> first.
>
> It's not useless.  The TSI code probes by device_type all over the
> place.  Do you have an example of how to probe for something like this
> without using device_type?

Sure: use "compatible" instead.

This problem is all over the place, don't worry
about it too much.  It would be good if new ports
could stop adding to the madness though ;-)

>>> +	  	MPIC: pic@7400 {
>>> +			built-in;
>>
>> Why say this for MPIC only, not for most other nodes?
>> What binding defines "built-in", anyway?
>
> http://playground.sun.com/1275/bindings/chrp/chrp1_8a.ps

But this isn't a CHRP compatible board, that binding
doesn't apply.

Segher