Re: Device-tree node renames break barebox/kernel compatibility...

[David Jander <david@protonic.nl>]

On Wed, 13 Jun 2018 08:42:30 +0200
Sascha Hauer <s.hauer@pengutronix.de> wrote:

> On Tue, Jun 12, 2018 at 03:46:06PM +0200, David Jander wrote:
> > On Tue, 12 Jun 2018 14:47:38 +0200
> > Sascha Hauer <s.hauer@pengutronix.de> wrote:
> >   
> > > Hi David,
> > > 
> > > On Tue, Jun 12, 2018 at 02:23:08PM +0200, David Jander wrote:  
> > > > 
> > > > Hi Sascha,
> > > > 
> > > > I know this is old already, and I was surprised that I couldn't find any
> > > > complaints about this yet, but I recently came across this patch in the kernel:
> > > > 
> > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/?id=df5cc9d0b42d15fa33b30440cca7a11ca7ba35a4
> > > > 
> > > > ...which was adopted in barebox as this:
> > > > 
> > > > https://git.pengutronix.de/cgit/barebox/patch/dts/src/arm/imx6qdl.dtsi?id=2e9cce8fb1f577088e2b20ae2f461130e13ad190
> > > > 
> > > > As I don't know the exact reason as to why this was necessary, or why this is
> > > > an issue at all, I just wanted to point out the fact that this leads to some
> > > > breakage in barebox new and old.    
> > > 
> > > This issue is known and has led to
> > > https://www.mail-archive.com/barebox@lists.infradead.org/msg25189.html  
> > 
> > Ah, thanks for the pointer. I had searched through the list archive since
> > september-2017 and did not find this... need new glasses anyway.
> >   
> > > > 
> > > > The specific problem I observed is here:
> > > > https://git.pengutronix.de/cgit/barebox/tree/net/eth.c#n299    
> > > 
> > > of_get_reproducible_name()/of_find_node_by_reproducible_name() is used for
> > > fixing up mtd partitions and state nodes, but not yet for the ethernet
> > > devices because nobody noticed.
> > > 
> > > To fix you would have to get a reproducible name of the ethernet device
> > > node from the barebox device tree using of_find_node_by_reproducible_name()
> > > and then use of_find_node_by_reproducible_name() on the kernel device
> > > tree.  
> > 
> > Ok, this makes sense. My only grief is that we are still left with a forced
> > bootloader update before being able to move to kernel 4.15+, for a reason
> > which to me doesn't sound really worth it.  
> 
> You can still revert the offending patch on your Kernel device trees.

I could, but it would be another patch to maintain against mainline...

> > Granted, the leading zero's are a
> > bit ugly and probably never should have made it mainline, but I don't
> > understand why the DT compiler should suddenly complain about that and can't be
> > fixed. In a way, the device-tree is an interface from the kernel to the outside
> > world, and while it is not really "user-space", IMHO it should still be
> > regarded stable and "set in stone"... but maybe that's just me?  
> 
> No, it's not just you. Me and other people are with you.
> 
> When talking about device tree stability we usually only talk about the
> bindings, not about the structure of the trees. The problem here was
> probably that people weren't aware that this change breaks stuff.

That's exactly what I also thought. That's in part also why I sent this e-mail
(the committers are in CC and hopefully listening ;-)
Sorry for the spam in that regard.

Best regards,

-- 
David Jander
Protonic Holland.

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