USB in latest kernel seems broken

Hi,

I am using direct USB connection as Ethernet between my host and beagle
board. In order to apply the DSP patches, I downloaded the omap-2.6 kernel
from kernel.org. But the latest kernel USB seems broken. I cannot get usb0
showing up in my host anymore.

v2.6.26-omap2 seems OK.
Latest kernel bad.

I did a bisect. I almost thought I found the commit. But I seems get
different result if bisect goes from bad version to one version vs from
good to that version.

I am doing the following thing:
export CROSS_COMPILE=cs2007q3-prefix

make distclean
make omap3_beagle_defconfig
make uImage

copy uImage to target
boot
check whether usb0 showing up in host.

Any thoughts? Is 'make distclean' a "deep clean"?

Thanks,
Guo