Comment 32 for bug 606238

Simon Dierl (simon.dierl) wrote :

#550625 addresses a slightly different type of hardware; the touchpad in question is identified as Product=0005 at /proc/bus/input/devices (ImPS/2 Generic Wheel Mouse). The touchpad in an E6510 reports Product=0001 (PS/2 Generic Mouse).
However, the root cause appears to be described at https://bugzilla.kernel.org/show_bug.cgi?id=14660 - apparently, newer ALPS touchpads use a new, undocumented and unsupported protocol. The touchpad falls back to a legacy emulation mode, resulting in faulty detections.
The kernel.org bug lists some efforts to reverse-engineer the protocol and has some patches based on DELL contributions that enable ImPS/2 emulation (scrolling works). This, however, still does not allow for synaptics support (turn off when typing, horizontal scroll, etc.). Additionally, some people report problems on suspend/resume.
The hardware detection used by the DELL patch in alps.c is:
{ { 0x73, 0x02, 0x64 }, 0x00, 0x00, ALPS_EC_PROTO }, /* Dell E2 series multitouch */
ALPS_EC_PROTO denotes a device memory access protocol used by the pads for initialization. It seems that this issue might affect all DELL E2 notebooks.