linux-kernel - Re: v4.1 to v4.7: regression in tsc2005 driver

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Date:	Wed, 20 Jul 2016 22:22:01 +0200
From:	Pavel Machek <pavel@....cz>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Michael Welling <mwelling@...e.org>,
	kernel list <linux-kernel@...r.kernel.org>,
	linux-input@...r.kernel.org, pali.rohar@...il.com, sre@...nel.org,
	aaro.koskinen@....fi, ivo.g.dimitrov.75@...il.com,
	patrikbachan@...il.com, serge@...lyn.com,
	Peter Hutterer <peter.hutterer@...-t.net>
Subject: Re: v4.1 to v4.7: regression in tsc2005 driver

Hi!

> > > > > > > > > drivers/input/touchscreen/tsc2005.c:	  input_dev->name = "TSC2005
> > > > > > > > > touchscreen";
> > > > > > > > > 
> > > > > > > > > to "TSC200X touchscreen". Unfortunately, X seems to propagate that
> > > > > > > > > name to userspace, where it is needed to be able to do
> > > 
> > > Technically X _is_ userspace.
> > 
> > There's "userspace running as root" and "userspace userspace" :-).
> 
> I do not really see any difference form the kernel POW. 
> 
> > 
> > > > > > > > > 
> > > > > > > > > xinput --set-prop --type=int ...
> > > > > > > > > 
> > > > > > > > > with the right arguments to calibrate touchscreen. (Touchscreen is
> > > > > > > > > unusable without calibration).
> > > > > > > > > 
> > > > > > > > > What to do with that?
> > > 
> > > Hmm, I do not think we ever committed for the device names to be stable.
> > > You are supposed to locate touchscreen device based on its properties
> > > and you might need some heuristic if you encounter a system with more
> > > than one such touchscreen.
> > 
> > Well, you are commited now, like it or not, X people did it for you
> > :-(.
> > 
> > Because there's no other reasonable way to use xinput --set-prop...
> 
> Well, X is going to have to fix it. How am I supposed to control my
> devices in multi-seat environment if I use the same hardware (or if I
> have device with multiple touchscreens)? They all will have the same
> name (well, all mice, then all keyboards, etc). Let's add Peter to the
> fold...

Well, if someone has such a multiseat config, they have a problem. But
in the meantime, I'd like to keep working system.

http://who-t.blogspot.cz/2016/07/xinput-resolves-device-names-and.html

And I see you replied in the blog. Good. Yes, X needs to be improved
to work nicely with multiseat. Still kernel needs to play nice and not
have regressions.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html