Re: [PATCH 2/2] Add the of_find_i2c_device_by_node function, V4

From: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
To: Jon Smirl <jonsmirl-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Linuxppc-dev-mnsaURCQ41sdnm+yROfE0A@public.gmane.org,
	Paul Mackerras <paulus-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>,
	i2c-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org
Subject: Re: [PATCH 2/2] Add the of_find_i2c_device_by_node function, V4
Date: Tue, 1 Jul 2008 18:44:24 +0200	[thread overview]
Message-ID: <20080701184424.40641cd0@hyperion.delvare> (raw)
In-Reply-To: <9e4733910807010938w67bab979tfba888641debe72f-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Tue, 1 Jul 2008 12:38:05 -0400, Jon Smirl wrote:
> On 7/1/08, Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org> wrote:
> > On Tue, 1 Jul 2008 11:12:58 -0400, Jon Smirl wrote:
> >  > On 7/1/08, Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org> wrote:
> >  > > I'm fine with this patch. In particular, exporting i2c_bus_type is OK.
> >  > >  It was un-exported only because it had no user left, but it can be
> >  > >  exported again if needed.
> >  >
> >  > Another solution would be to move drivers/of/of_i2c into the i2c
> >  > directory and make it part of i2c core on powerpc builds.
> >
> > I don't think this is a good idea. Merging arch-specific code (or
> >  half-arch-specific code in this case) into arch-neutral drivers ends up
> >  being a pain to maintain. People will keep sending me patches for stuff
> >  I don't know anything about and can't help with. Having of-specific
> >  stuff in just one directory as is the case now sounds much better to
> >  me. All it's missing is a MAINTAINERS entry.
> 
> A side effect of this is that the small pieces of code in drivers/of
> have to be compiled into stand alone modules and they may need access
> to internal symbols from the subsystem. If they were directly linked
> into the subsystems you wouldn't need to make the internal symbols
> visible.

Do you think you'll need something else than i2c_bus_type? That I don't
consider an i2c-core internal. As I said, the lack of export was simply
due to a lack of user.

> Now the subsystems have to be careful about breaking the
> in-kernel, external users of the symbols

Same holds if the code is merged into i2c-core.

> and we've made it possible for out of tree drivers to get to internal
> structures.

Hopefully the namespaced exports which some kernel developers are
working on, will become a reality soon, to mitigate that kind of issue.
That being said...

As an upstream kernel developer / maintainer, I don't care about that.
If external modules make use of internals they shouldn't touch, and
later changes cause them to break, that's none of my business. I leave
this to distribution maintainers.

-- 
Jean Delvare

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