Beagleboard stable USB EHCI hack

Occasionally, the USB EHCI controller on a Rev C3 Beagleboard stops working until the system is rebooted. It is usually triggered by heavy traffic, e.g. due to a WLAN dongle or a USB thumbdrive. It was apparently fixed properly in Rev C4, but if you're stuck with a C3 board the following hack may solve the problem for you.

The error is due to noise on the VDD2 power rail (1.8 V). Too many events occuring simultaneously may cause the power rail to dip, which in turn causes the USB PHY to panic. One way to lower the probability of this is to increase the capacitance of the power rail near the USB PHY.

As you can see in the picture, I've soldered a 10 uF electrolytic capacitor across C97, thus increasing the capacitance from 10 uF to 20 uF. The capacitor is oriented with the positive side towards the SD card slot, but you may want to verify this yourself using a voltmeter on a running system.

Be careful, and don't blame me if you mess it up. But if you do, you now have a valid reason to buy a Rev C4 board. =)

The capacitance hack was suggested in this usenet thread, along with much other speculation.