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Aspire 5520 Alps Touchpad Joystick

Just realized that I have not posted “this thing works under linux”-style note for my brand new Acer Aspire 5520G. So far I have managed to migrate my data completely from my old Acer Aspire 3000LC, brought wifi up and now I am happily using it

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There are some minor issues, though. My old laptop featured outstanding Synaptics touchpad which was not only supported by linux but the manufacturer actually provided all the required information for drivers to be written. This turned out not to be the case with Alps. Although their device is PS/2 one, reverse-engineering was required to get it working. It is now supported by linux kernel psmouse module (if you enable CONFIG_MOUSE_PS2_ALPS) but for me it looks like support is not complete. While I am not yet sure what exacly drives me mad about it, be it low sensitivity when you need high one or accidental tapping when you touch it as light as possible with our palm…

One thing that is now actually missing is support for four-direction joystick located between left and right “mouse” buttons. By default joystick works partially, vertical axis is upside-down and horizontal axis does not generate any events. So I took advantage of my sick day off and added support for correct processing of touchpad joystick events. Here’s my /proc/bus/input/devices entry:

I: Bus=0011 Vendor=0002 Product=0008 Version=7325 N: Name="AlpsPS/2 ALPS GlidePoint"

You can download the updated kernel patch here: alps-aspire5220-take2.patch. You will not need to patch synaptics X.org driver. As a drawback, it also affects Dell Vostro 1400 which contains the same touchpad hardware, but it is missing the joystick completely (according to what I saw on the pictures posted). So this should not be an issue.

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