Touchpad and i8042

Hi all,

I've noticed a weird behaviour when monitoring roughly the number of interrupts fired. The number of interrupts for "i8042" increase dramatically when I move the pointer using the touchpad.

I've only used "watch cat /proc/interrupts".

dramatically = ~800 interrupts
for only moving the finger from the top to the bottom of the touchpad.

I'm using kernel 2.6.21.1, don't know if this happened before - I noticed it now.

The interrupts only appear on touchpad usage, not on standby.

I think it is a synaptics touchpad, but I'm not really sure (how could I find out?)

Does anyone have an explanation for this? I've seen the "appletouch" problem problem on the linuxpowertop.org site but I don't know if they're related.

If any other info is needed, let me know.

Mircea

The touchpad is attached to an i8042. When you touch it, it sends data and generates interrupts. That's perfectly normal.

Matthew Garrett | [email protected]

Yep. With Synaptics touchpad that by default has 80 pps @ 6 bytes per packet you should be getting ~480 interrupts per second.

Dmitry