i2c_hid: Possible workaround to Synaptics touchpad going wild on Acer Aspire

[Andrea Monaco <andrea.monaco@autistici.org>]

Hello,


as I wrote in previous emails to this list, my Synaptics touchpad
(SYN1B7F) on Acer Aspire laptop sometimes starts acting wild, it moves
and clicks and drags on its own.  I can't find any trigger for this
behavior, it just happens.

I see long sequences of HID reports that are identical expect for the
timestamp when this happens; my hypothesis is that the issue is on the
hardware, possibly a buggy firmware of the touchpad.

Unloading and reloading i2c_hid solves the issue, probably because it
triggers a hardware reset of the device.


So I came up with a possible workaround: any time the kernel detects two
consecutive HID reports that are identical except for the timestamp, it
hard resets the device.  The user would experience a very brief
discontinuity in mouse response, still much better than current
behavior.

This particular hack could be activated with an option to the relevant
module(s), or when the affected touchpad models are found.


Any comments or suggestions?



Warmly,

Andrea Monaco