Update: 11/09/2009
Installed Snow Leopard 10.6.2 into my Dell Inspiron 1420.
Tryed bcc9 64 bits kext from here:
http://forum.voodooprojects.org/index.php/topic,718.0.htmlt, but trackpad didn't worked for me (just went crazy).
so here's my originally modified kext compiled for 64 bits Snow.
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ORIGINAL POST
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Ok, here's what i did to make my ALPS working on an Inspiron 1420.
First some debugging info i've got after a few hours:
1- My ALPS glidepoint is detected as ALPS, but then in probe() IsItALPS returns false.
2- This ALPS uses absolut mode, but in interruptOcurred is detected as relative and uses 3 UInt8 packets, and discards 3 more packets, sometimes, depending on data, it doesn't discards three, but detects them as a packet, reading garbage. Commenting those lines makes interruptOcurred call absolutwithpacket (or something like that) with a 6 item array. It starts working at this point.
3- in ApplePS2ALPSGlidePoint::setParamProperties(): eaccell value is 0, so _edgeacellvalue is never set. This makes scrolling unavailable (accelleration is 0, so it never moves).
4- In ApplePS2ALPSGlidePoint::dispatchAbsoluteEventWithPacket() where it calculates the ydiff and xdiff there is somewere a comparation with SCROLL_HORIZ and SCROLL_VERT: that calc takes ydiff and xdiff back to zero, disabling scrolling.
5- In ApplePS2ALPSGlidePoint::dispatchAbsoluteEventWithPacket(), the Z variable doesn't represent touch pression (doesn't know what represents yet). So tapping doesn't work. Instead, first bit at 3rd item in packet array represents the tapping (packet[2] & 1). I used that to simulate a left button click.
With all these modifications, and some constants to make my trackpad a bit slower, I "patched" ApplePS2ALPSGlidePoint.cpp to make my touchpad work. (I said "patched" because it's a crapy code just for me, but this info may guide the vooodoo team to a fully working ALPS driver)
hope it helps, someone.