Gathan Beaga

macbook trackpad problem

Had a little bit of trouble with the MacBook this evening.

R. had been using it as she usually does during the day: every so often lifting the lid (thus waking it up) and checking the email. During one such email check, the mouse pointer suddenly froze, and she got the “I’m busy” spinning beachball that MacOSX uses to let the user know it’s up to something.

Nothing she could do seemed to start it working again, so she left it alone. Strangely enough, it went to sleep not long afterward, so whatever was causing the problem wasn’t locking the entire system.

When I got home I woke it up to have a bit of a look. It looked like both the trackpad and the keyboard weren’t working. I tested using an external mouse and keyboard: both worked fine.

Maybe there was something wrong with one of the internal USB buses? I checked using both Apple System Profiler, and the USBProbe app from the Developer Tools… but I couldn’t really understand what I was looking at.

I then tried to decipher the system logs – there were lots of cryptic messages like this:

Aug 30 17:12:15 MacBook kernel[0]: USBF: 117373.645 AppleUSBUHCI[0x36fe000]::DoControlTransfer sync request on workloop thread. Use async!

I tried to uninstall Sidetrack, the third party trackpad driver that I prefer to use. (It turned out that I didn’t properly uninstall it, as I found out later, but it’s hard to know if this is significant or not.)

Now what?

I searched online and couldn’t find anything useful. (There’s not many unique keywords for searching on this subject that I could think of using that don’t come up with a whole lot of false positives.)

Then I remembered the voodoo of the PMU, and the resetting thereof. At some point in the past I had researched this during some previous troubleshooting binge, I think for the iBook when it had its second lot of logic board issues. So, the Power Management Unit:

…is an integrated circuit (computer chip) that is on the logic board of the MacBook or MacBook Pro. As the name implies, it is responsible for power management of the computer. It controls backlighting, hard disk spin down, sleep and wake, some charging aspects, trackpad control, and some input/output as it relates to the computer sleeping.

Aha! Trackpad control?!

So, following the instructions, I reset the Power Management Unit.

And… all was well.

I even reinstalled SideTrack (after uninstalling it properly using the SideTrack installer), and still all was well.

Phewf. Two and a half hours later.