Re: [PATCH V3 2/3] regulator: dt: regulator match by regulator-compatible

[Mitch Bradley <wmb-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org>]

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On 6/21/2012 9:45 AM, Mark Brown wrote:
> On Thu, Jun 21, 2012 at 05:17:45PM +0000, Arnd Bergmann wrote:
>> On Thursday 21 June 2012, Mark Brown wrote:
>
>>> I'm not that big a fan of moving all the data into device tree as it
>>> means that you need even more parsing code and you need to update the
>>> device trees for every board out there every time you want to add
>>> support for a new feature which doesn't seem like a win.


Maybe I'm missing something, but in general it's not necessary to update 
old device
trees to support new features.  The trick is to define a new property 
that describes
the new possibility.  Absence of that property implies that the default 
- the thing
that used to happen across the board, before the feature existed - applies.

>>>   Right now with
>>> the DT kept in the kernel it's not so bad but if we ever do start
>>> distributing it separately it becomes more of an issue.
>
>> Right. It's certainly a trade-off. If a company makes 100 SoCs that
>> all have similar-but-different regulators, then it should be clear
>> win to have the driver be very abstract and fed with DT data for
>> configuragtion.
>
> Well, nobody does that anyway but even if they were it doesn't help
> non-DT systems at all, nor does it help when we need to go and add new
> properties to every existing device tree using the device.  We've got
> far more architectures don't use DT than do...
>
>>> I'm also not sure if the tooling works well for allowing people to
>>> include standard DTs for chips and add new properties to nodes for the
>>> board specific configuration, though I think I've seen a few things
>>> which suggested that was dealt with reasonably well.
>
>> It should never be necessary to add board-specific properties in the
>> nodes that describe the SoC specific bits. What I was referring to
>> is just moving the data that currently resides in the regulator
>> driver into DT.
>
> How would this work given that we also need to put system specific
> configuration for the same devices into DT?  As Stephen says it doesn't
> seem to match what we're currently doing.
>
>
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