Re: New Alps protocol in the wild?

[Ben Gamari <bgamari.foss@gmail.com>]

Seth Forshee <seth.forshee@canonical.com> writes:

> On Fri, Jul 27, 2012 at 12:18:51PM -0400, Ben Gamari wrote:
>> Recently I took shipment of a Dell Latitude E6430 (supposedly
>> "certified" by Canonical). Sadly, out of the box the multitouch-capable
>> Alps Dualpoint mouse is detected as a generic PS/2 device (bug filed
>> here[1]). After a bit of poking around I figured out the signature
>> ({0x73, 0x03, 0x0a}) and command_mode_resp (0x1d) of the device.
>> 
>> Based on the other recent Dell models listed in alps_model_data, I tried
>> configuring the device as a protocol v3 device. While in appearance the
>> driver succeeded in configuring the device, it was clear that it was
>> still operating in bare PS/2 mode (only bare PS/2 reports were received
>> and 0x04 register was read to be 0x00 --- assuming the register read
>> command is correct).  This is supported by Seth's alps-reg-dump tool[2],
>> which declares that the device is "Not a v3 ALPS touchpad".  Trying to
>> configure the device with protocol v4 resulted in the driver to fail
>> during configuration (failing to enter absolute mode).  Given this
>> evidence, it seems fairly clear that this device differs appreciably
>> from any device currently supported by alps.c.
>
> That's likely. It's known that there's at least one ALPS protocol
> version that isn't supported.
>
I suspected that was the case.

>> I've tried to collect PS/2 traces from a Windows 7 installation running
>> under a patched Qemu[3]. Unfortunately, while Windows running on bare
>> hardware configures the device perfectly, an installation from the same
>> media seems to treat the device as a bare PS/2 device when running under
>> virtualization. The PS/2 trace produced clearly shows the driver probing
>> the device as an Intellimouse and failing that falls back to generic
>> PS/2 reports. Can anyone think of what might have changed between the bare
>> metal and the virtualized environment?
>
> I'm thinking that when I was looking at the initialization from Windows
> drivers it would first initialize it like a normal PS/2 mouse then later
> the ALPS initialization would show up, almost like the default driver
> ran through it's initialization first before the ALPS driver did. Did
> you look further down in the logs to see if anything similar to the ALPS
> initialization is happening later?
>
Sadly no. The driver comes with a configuration tool which when launched
appears to trigger a reconfiguration.

> Otherwise I don't have any ideas off the top of my head. This approach
> generally worked fine with the machines/drivers I worked with.
>
Hmmm, that is truly unfortunate. I guess given this I'll just have to
try piecing together a filter driver and collect the initialization
process on bare metal. Hopefully at that point I'll be able to do the
reversing of the data format over serio.

>> I would love to take a stab at reversing this protocol variant, but
>> the inability to get a trace from a virtualized working configuration is
>> a real blocker. I suppose I could try writing a Windows filter driver
>> but the virtualization approach seems orders of magnitude more
>> convenient. Any ideas would be greatly appreciated.
>> 
>> As a final note, I have read various places that ALPS had intended on
>> releasing a closed source driver for some of their devices. Has anything
>> happened on this front? Perhaps it would be easier to get a trace from a
>> closed-source driver running on Linux than a closed-source driver
>> running on Windows.
>
> I've heard that such a driver exists, but I don't know where you can get
> it. I _think_ some factory preinstalled Linux systems might ship with
> it, so it's possible that it's something ALPS provides to its customers
> but doesn't make publicly available.
>
Naturally. I never would have suspected that such a despicable company
could be found in making something as innocuous as touchpads. Sheesh.

Given the difficulty of the reverse engineering process and the
proliferation of incompatible hardware variants, it seems a major
customer really needs to step up and demand some sanity from these
people. My understanding is that Dell currently does not have access to
Alps specifications but given the volume they move it seems they are in
a fairly unique position to exert pressure. Being a Dell partner, has
Canonical taken any steps to start this dialogue?

On that note, Canonical's certification certificate for the E6430 is
currently incorrect. The desktop program guidelines clearly state that
vertical scroll is on the grey list yet, as far as I can tell, the
certificate makes no mention of the lacking support of the input
hardware of this model.

Cheers,

- Ben