linux-kernel - Re: [PATCH RESEND] Input: ALPS - Fix two-finger scroll breakage in right side on ALPS touchpad

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Date:   Fri, 25 Aug 2017 10:37:31 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Pali Rohár <pali.rohar@...il.com>,
        Masaki Ota <masaki.ota@...alps.com>,
        Paul Donohue <linux-kernel@...lSD.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] Input: ALPS - Fix two-finger scroll breakage in right side on ALPS touchpad

On Fri, 25 Aug 2017 01:09:55 +0200,
Dmitry Torokhov wrote:
> 
> Hi Takashi,
> 
> On Tue, Aug 22, 2017 at 10:17:00PM +0200, Takashi Iwai wrote:
> > From: Masaki Ota <masaki.ota@...alps.com>
> > 
> > Fixed the issue that two finger scroll does not work correctly
> > on V8 protocol. The cause is that V8 protocol X-coordinate decode
> > is wrong at SS4 PLUS device. I added SS4 PLUS X decode definition.
> > 
> > Mote notes:
> > the problem manifests itself by the commit e7348396c6d5 ("Input: ALPS
> > - fix V8+ protocol handling (73 03 28)"), where a fix for the V8+
> > protocol was applied.  Although the culprit must have been present
> > beforehand, the two-finger scroll worked casually even with the
> > wrongly reported values by some reason.  It got broken by the commit
> > above just because it changed x_max value, and this made libinput
> > correctly figuring the MT events.  Since the X coord is reported as
> > falsely doubled, the events on the right-half side go outside the
> > boundary, thus they are no longer handled.  This resulted as a broken
> > two-finger scroll.
> > 
> > One finger event is decoded differently, and it didn't suffer from
> > this problem.  The problem was only about MT events. --tiwai
> > 
> > Fixes: e7348396c6d5 ("Input: ALPS - fix V8+ protocol handling (73 03 28)")
> > Signed-off-by: Masaki Ota <masaki.ota@...alps.com>
> > Tested-by: Takashi Iwai <tiwai@...e.de>
> > Tested-by: Paul Donohue <linux-kernel@...lSD.com>
> > Cc: <stable@...r.kernel.org>
> > Signed-off-by: Takashi Iwai <tiwai@...e.de>
> > ---
> > 
> > Dmitry, I resend this patch from Ota-san, as the previous thread was
> > cursed.  Since this is an annoying regression in the recent kernels,
> > could you apply this?  Thanks!
> 
> Sorry I checked out on this patch for a bit. It is now applied and I
> will send it Linuswards in the next day or two.
> 
> Thanks!

Great, thanks!


Takashi