From: Ondrej Zary <linux@rainbow-software.org>
To: Eric Wong <normalperson@yhbt.net>
Subject: Re: BYD TouchPad driver (4.8.1) misdetects a Logitech mouse
Date: Fri, 11 Nov 2016 08:56:20 +0100
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Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        chris@diamand.org, Michael Shell <list1@michaelshell.org>
References: <20161015232444.7727e5f78910e8c610019143@michaelshell.org> <20161111015757.GA10859@dcvr.yhbt.net>
In-Reply-To: <20161111015757.GA10859@dcvr.yhbt.net>
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On Friday 11 November 2016, Eric Wong wrote:
> Sorry for the late response, forwarding to Dmitry and linux-input.
> I haven't dealt with input in years...
>
> Michael Shell <list1@michaelshell.org> wrote:
> > Not a big deal, but something nonetheless ...
> >
> > I recently upgraded my kernel from 4.3 to 4.8.1 (this is a Linux From
> > Scratch build). There was only one obvious hiccup - X would not
> > start because it no longer saw the mouse.
> >
> > I have a Logitech RX250 PS2/USB mouse on the PS/2 port (via a USB->PS2
> > adapter):
> >
> > http://support.logitech.com/en_gb/product/rx250-mouse
> >
> > The RX250 is a wheel mouse, but with an added left/right scroll wheel
> > "tilt" feature to provide for horizontal scrolling.
> >
> > In my xorg.conf I had:
> >
> >
> > Section "InputDevice"
> >         Identifier      "Mouse0"
> >         Driver          "evdev"
> >         Option          "Name"  "ImExPS/2 Logitech Explorer Mouse"
> > EndSection
> >
> >
> > However, under the 4.8.1 kernel, cat /proc/bus/input/devices shows:
> >
> >
> > I: Bus=0011 Vendor=0002 Product=0006 Version=0073
> > N: Name="ImExPS/2 BYD TouchPad"
> > P: Phys=isa0060/serio1/input0
> > S: Sysfs=/devices/platform/i8042/serio1/input/input3
> > U: Uniq=
> > H: Handlers=mouse0 event2
> > B: PROP=1
> > B: EV=7
> > B: KEY=1f0000 0 0 0 0 0 0 0 0
> > B: REL=143
> >
> >
> > and dmesg shows the lines:
> >
> >
> > psmouse serio1: logips2pp: Detected unknown Logitech mouse model 115
> > input: ImExPS/2 BYD TouchPad as
> > /devices/platform/i8042/serio1/input/input3
> >
> >
> > Changing the mouse name in xorg.conf to "ImExPS/2 BYD TouchPad" did
> > allow the mouse to work correctly under X, including the tilt buttons.
> > FWIW, in the 4.8.1 kernel config, the byd.c driver does default to
> > "Yes", a default which I accepted under make oldconfig.
> >
> > Apparently, the detection code (byd_detect) in the new byd.c driver,
> > which did not even exist in 4.3, (drivers/input/mouse/byd.c) falsely
> > sees the Logitech RX250 as being a BYD TouchPad and thus alters the
> > vendor and model names.
> >
> > I do not know if it is also desirable to add an entry for a Logitech
> > model 115 in get_model_info in logips2pp.c
> > (drivers/input/mouse/logips2pp.c). But if so, I would be willing to
> > test any such new code. Even as an unknown Logitech model, it does
> > work just fine. I am curious as to how the tilt feature buttons would
> > be declared in the model info (would these be PS2PP_EXTRA_BTN,
> > or PS2PP_NAV_BTN, etc.?)
> >
> >
> >
> >   Cheers and thanks in advance,
> >
> >   Mike Shell

The BYD detection is broken. I've seen at least 3 different mice detected as 
BYD touchpad.

-- 
Ondrej Zary