Re: DT bindings as ABI [was: Do we have people interested in devicetree janitoring / cleanup?]

From: Jason Gunthorpe
Date: Mon Jul 29 2013 - 14:41:02 EST

On Mon, Jul 29, 2013 at 07:16:07PM +0100, Russell King - ARM Linux wrote:

> What does it take? Good practice, care, thought and planning. All
> the qualities which should already be present for kernel _engineers_.
> Not an "lets create something for me, I don't care about anyone else"
> attitude.

I agree with what you've written, but we are looking at this from
different ends of the problem.

I fully agree you can create a main line kernel GIT tree that has a
stable DT ABI.

However, I as an ODM, with time pressure, cannot wait for the kernel
folks to finish this work. So from my perspective the DT will not be
stable, as I will put whatever interm stuff I choose to have a
shippable product.

Thus I have to design my systems for an unstable DT, and the message
from the kernel community to people in my posistion should be:

When you ship early with non-mainlined DT schema, design your boot
system around an unstable DT. Plan to migrate your DT to upstream
once it becomes finalized.

Here is the rub: Once I design for an unstable DT I simply don't
derive value from the kernel communities work to create a stable DT.

So who is getting the benefit of this work, and is it worth the cost?

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