Re: ALPS touchpad ot correctly recognized: GlidePoint vs DualPoint

["Pali Rohár" <pali.rohar@gmail.com>]

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On Thursday 07 September 2017 23:31:23 Dmitry Torokhov wrote:
> Hi Juanito,
> 
> On Thu, Sep 07, 2017 at 09:05:14AM +0200, Juanito wrote:
> > Dear Kernel Hackers,
> > 
> > I hope this is the correct place to post this. If not, please
> > forgive me and feel free to forward it to someplace else. Thank
> > you very much!
> 
> Let's add a few more people who's been looking after ALPS...
> 
> > I have a ThinkPad with a touchpad that looks exactly like this:
> > https://www.camerongray.me/wp-content/uploads/2015/02/SCotlGg.jpg
> 
> > The three pyhsical buttons on top do not work on my debian stretch
> > (4.9). I think it isn't being recognized correctly. I see a
> > "Rejected trackstick packet from non DualPoint device" in my
> > syslog whenever I click on one of them. On the other hand on a
> > Ubuntu 16.04 (4.4 - patched by Ubuntu y guess) the buttons *do*
> > work. Interestingly enough, it doesn't work on 17.04 (4.10).

ThinkPad with ALPS? Should not be it Synaptic? Maybe miss-detection?

Anyway, for ALPS devices, buttons below touchpad area are reported from 
touchpad device and buttons above touchpad are reported from the 
trackstick device.

ALPS DualPoint means device with touchpad + trackpoint

ALPS GlidePoint means device with only touchpad (without trackpoint)

So error message "Rejected trackstick packet from non DualPoint device" 
which is generated at time when you click at buttons, would mean that 
those buttons are reported via trackstick. And if kernel detected that 
ALPS device as GlidePoint, then events from trackpoint (so also buttons) 
are dropped.

> > I have noticed that the touchpad gets assigned different names on
> > both distros. On debian it is recognized as a GlidePoint and on
> > Ubuntu as a DualPoint. In an upstream kernel 4.13 which I just
> > built, it's also recognized as a GlidePoint. Unfortunately it
> > doesn't work either.

Name is assigned based on detection if trackstick is present. Different 
kernel versions is probably reasons, maybe one version has wrong 
detection.

Is trackstick movement working? This is probably important to know as it 
looks like buttons are reported via trackstick, not via touchpad.

> > I am not sure if the device is actually a DualPoint or not (I don't
> > really understand the terminology here), but the thing is that the
> > buttons work when the kernel believes it to be one.
> > 
> > This is the info I have managed to find about the device while
> > running on the non-working debian:
> > 
> > dmesg:
> > [    2.914806] input: AlpsPS/2 ALPS GlidePoint as
> > /devices/platform/i8042/serio1/input/input2
> > 
> > lsinput:
> > /dev/input/event11
> > 
> >    bustype : BUS_I8042
> >    vendor  : 0x2
> >    product : 0x8
> >    version : 1792
> >    name    : "AlpsPS/2 ALPS GlidePoint"
> >    phys    : "isa0060/serio1/input0"
> >    bits ev : (null) (null) (null)
> > 
> > I have played around with the drivers/input/mouse/alps.c file and
> > found out the following:
> > 
> > e7 and ec are important (although I don't know what these are
> > exactly) and have the following values:
> > 
> > e7: 73 03 0a
> > ec: 88 b0 13

Masaki should know exact type of device...

> > This combination is recognized as an ALPS touchpad, but isn't
> > assigned the ALPS_DUALPOINT flag. As far as I can see, it is
> > actually being *removed* at this point:
> > 
> > if (alps_probe_trackstick_v3_v7(psmouse, ALPS_REG_BASE_V7) < 0)
> > 
> >             priv->flags &= ~ALPS_DUALPOINT;
> > 
> > The bit that says it has a trackpoint (I don't know what this is)
> > is apparently saying my device doesn't have one and is removing
> > the ALPS_DUALPOINT flag.

At least for V3 protocol that function tells touchpad to enable pass-
thru mode to trackstick and detect if trackstick is there present. After 
that leave pass-thru mode.

> > This flag makes the buttons work. I am not sure if it breaks other
> > stuff.

Is that picture of your laptop, do you really have trackstick working?

My idea is that alps_probe_trackstick_v3_v7 does not check presence of 
trackstick correct and return information that trackstick is not present 
(which contains also those buttons)...

Masaki, can you confirm if there can be problem with that function?

> > I have written a pretty dummy patch which actually adds the flag
> > again making the buttons work. Again, I am not sure if it breaks
> > other stuff but my system isn't whining. Here is the patch:
> > 
> > diff --git a/drivers/input/mouse/alps.c
> > b/drivers/input/mouse/alps.c index 850b00e3ad8e..17aba42e846f
> > 100644
> > --- a/drivers/input/mouse/alps.c
> > +++ b/drivers/input/mouse/alps.c
> > @@ -2804,6 +2804,9 @@ static int alps_set_protocol(struct psmouse
> > *psmouse,
> > 
> >                 if (alps_probe_trackstick_v3_v7(psmouse,
> > 
> > ALPS_REG_BASE_V7) < 0)
> > 
> >                         priv->flags &= ~ALPS_DUALPOINT;
> > 
> > +               if (priv->fw_ver[1] == 0xb0)
> > +                       priv->flags |= ALPS_DUALPOINT;
> > +
> > 
> >                 break;
> >         
> >         case ALPS_PROTO_V8:
> > After applying this patch dmesg and lsinput say this:
> > 
> > [    8.226543] input: AlpsPS/2 ALPS DualPoint Stick as
> > /devices/platform/i8042/serio1/input/input13
> > [    8.247595] input: AlpsPS/2 ALPS DualPoint TouchPad as
> > /devices/platform/i8042/serio1/input/input2
> > 
> > /dev/input/event11
> > 
> >    bustype : BUS_I8042
> >    vendor  : 0x2
> >    product : 0x8
> >    version : 1792
> >    name    : "AlpsPS/2 ALPS DualPoint Stick"
> >    phys    : "isa0060/serio1/input1"
> >    bits ev : (null) (null) (null)
> > 
> > /dev/input/event12
> > 
> >    bustype : BUS_I8042
> >    vendor  : 0x2
> >    product : 0x8
> >    version : 1792
> >    name    : "AlpsPS/2 ALPS DualPoint TouchPad"
> >    phys    : "isa0060/serio1/input0"
> >    bits ev : (null) (null) (null)
> > 
> > I am a total newbie to kernels and drivers so it would be great if
> > somebody who actually had some idea could take a look at this and
> > probably create a patch in a better place. I'll be glad to post
> > more info if necessary.
> > 
> > Thank you very much!
> > 
> > Cheers,
> > Juanito
> > 
> > --
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> > linux-input" in the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
Pali Rohár
pali.rohar@gmail.com

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