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From:   Ondrej Zary <linux@rainbow-software.org>
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: Re: Sony Vaio VGN-CS31S touch sensor buttons breaking touchpad
Date:   Mon, 2 Apr 2018 23:19:02 +0200
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On Monday 02 April 2018 23:05:29 Dmitry Torokhov wrote:
> On Mon, Apr 02, 2018 at 10:39:59PM +0200, Ondrej Zary wrote:
> > On Sunday 01 April 2018 23:21:55 Ondrej Zary wrote:
> > > Hello,
> > > I got a Sony Vaio VGN-CS31S laptop with Synaptics touchpad that
> > > exhibits weird behavior. It seems to work until I touch the "Touch
> > > Sensor Buttons" bar above the keyboard - then the buttons start to act
> > > weirdly: click or remain pressed (sometimes it breaks even without
> > > touching the bar).
> > >
> > > It seems to be a known problem with VGN-CS series:
> > > https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-input-synaptics/
> > >+bug /774877
> > > https://wiki.freegeekvancouver.org/article/Laptop_Troubleshooting
> > > (mentions nasty partial workaround: psmouse.resetafter=1)
> > >
> > > Many models of the VGN-CS series have the Touch Sensor Buttons:
> > > ftp://124.40.41.224/PUB/MANUALS/SWT/Z009/Z009690111.PDF
> > >
> > > From the hardware side (can be found in MBX-196 Quanta GD2 schematic),
> > > the touch bar is a separate PS/2 device connected to third PS/2 port of
> > > the EC (Embedded Controller) WPC775L. The touchpad is on the 1st PS/2
> > > port, 2nd port is unused. However, the i8042 does not seem to support
> > > multiplexing, the firmware probably combines the data internally
> > > somehow.
> >
> > Good news: it supports multiplexing but i8042_nomux is set because of:
> >                 /*
> >                  * Most (all?) VAIOs do not have external PS/2 ports nor
> >                  * they implement active multiplexing properly, and
> >                  * MUX discovery usually messes up keyboard/touchpad.
> >                  */
> >                 .matches = {
> >                         DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
> >                         DMI_MATCH(DMI_BOARD_NAME, "VAIO"),
> >                 },
> > in drivers/input/serio/i8042-x86ia64io.h
> > (How can this be modified to exclude VGN-CS series?)
>
> I guess we'd need a whitelist for MUXes, because older VAIOs would
> behave really really badly when one tried to probe for active
> multiplexing...
>
> If you enable MUX, does it survive suspend/resume?

Yes, suspends and resumes fine.

(Suspend takes 20-25 seconds after the HDD stops but it's the same regardless 
of MUX.)

-- 
Ondrej Zary