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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