Frantisek Burian 0cc0134f21 usb: Only enable the SOF interrupt if user_callback_sof is given.
Otherwise we get 1 kHz of SOF interrupts even if we don't need them.

Originally reported by Uwe in https://github.com/libopencm3/libopencm3/pull/274
but BuFran provided a reworked implementation.
2015-07-15 00:22:18 +00:00
..