Re: [PATCH] serdev: fix builds with CONFIG_SERIAL_DEV_BUS=m

[Johan Hovold <johan@kernel.org>]

On Wed, Dec 18, 2019 at 10:29:58AM +0100, Uwe Kleine-König wrote:
> On Wed, Dec 18, 2019 at 10:06:06AM +0100, Johan Hovold wrote:
> > On Wed, Dec 18, 2019 at 09:38:42AM +0100, Uwe Kleine-König wrote:
> > > Commit 54edb425346a ("serdev: simplify Makefile") broke builds with
> > > serdev configured as module. I don't understand it completely yet, but
> > > it seems that
> > > 
> > > 	obj-$(CONFIG_SERIAL_DEV_BUS) += serdev/
> > > 
> > > in drivers/tty/Makefile with CONFIG_SERIAL_DEV_BUS=m doesn't result in
> > > code that is added using obj-y in drivers/tty/serdev/Makefile being
> > > compiled. So instead of dropping $(CONFIG_SERIAL_DEV_BUS) in serdev's
> > > Makefile, drop it in drivers/tty/Makefile.
> > 
> > Why not simply revert the offending patch? There are some dependencies
> > here related to how the tty layer is built. If you're still not certain
> > on why things broke, I suggest just reverting for now.
> 
> I see that it is not easy to define what obj-y should do in a Makefile
> that is included via obj-m. Now it is the other way round and that
> should be safe. This construct is used in several places, so I'd say the
> patch is fine unless you have more concrete concerns.

No, and I don't have time to look into this right now.

It's more about the general principle that a patch should do one thing;
in this case unbreak the build. If you want to do cleanups as well, you
do that separately (and argue for why its needed).

Johan