r264 patch was blind, since I haven't appropriate hardware :(
If your webcam don't work in r273 at all, seems to be uhci/ohci drivers requires urb->next, but ehci can't work with it :( This situation already resolved in 2.6 kernels, and I should to look into drivers code, but it may consume much time. As fast solution I can revert r264 patch only.
Aboutor -EPIPE error code - I can only suggest remote debugging, since this error never be observed myself since 232-usb-hub11.patch applied.PHP Code:
usb.c: unable to get device descriptor (error=-32)
i.e. I build debug firmware - you runs it and send back to me debug messages. If it is acceptable for you - drop me private message.