Marc Gonzalez <marc_gonzalez@xxxxxxxxxxxxxxxx> writes:
>>> So I should write something like this in my DT?
>>>
>>> eth0: ethernet@26000 {
>>> compatible = "sigma,smp8734-ethernet", "sigma,smp8640-ethernet", "aurora,nb8800";
>>>
>>> Hmmm, you mention this below, but you used "sigma,smp8759-ethernet".
>>> What about earlier chips?
>>
>> OK, how about this scheme then:
>>
>> - Device trees list the exact chip, the chip family, the oldest
>> compatible family, and finally the basic "aurora,nb8800". For the
>> SMP8759 that would look like this:
>> "sigma,smp8759-ethernet", "sigma,smp87xx-ethernet", "sigma,smp864x-ethernet",
>> "aurora,nb8800"
>
> AFAICT, the list of tango4 chips is (in chronological order)
>
> 8910, 8734, 8756, 8758, 8759
>
> The problem I see is that Sigma already has plans for non-tango4
> 87xx SoCs (two in fact: 8760 and 8762, as far as I've heard).
> (What a mess.)
>
> I would think the "chip family" needs to use the code-name like
> tango3 or tango4 (for lack of a better discriminant).
>
> Also, (purely hypothetical) suppose something changed in 8756 and up.
> How would the 8758 pick up the improvement, but not the 8734?
>
> I'm also confused, because I thought I read somewhere not to use
> wildcards in compatible strings... <Looking> It was there:
> http://devicetree.org/Device_Tree_Usage#Understanding_the_compatible_Property
> (Sorry, some of this stuff is a bit hard for me to grok.)
Right, and you just illustrated why wildcards are bad. Sorry for the
confusion. I should have known better than to look at existing
bindings. Let's drop that idea.
Let's try something else:
Device trees list the exact chip, the oldest chip with the same
features, and the oldest compatible chip. From the sound of things,
that means the smp8759 should use "sigma,smp8759-ethernet",
"sigma,smp8910-ethernet", "sigma,smp8642-ethernet", "aurora,nb8800".
> Finally, I think what you decide to do can also be done for the
> interrupt controller, right?
Sure, the same scheme should be used for all on-chip devices.
--
Måns Rullgård
mans@xxxxxxxxx
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