Provided by:
linux-doc-2.6.15_2.6.15-23.39_all 
NAME
usb_claim_bandwidth - records bandwidth for a periodic transfer
SYNOPSIS
void usb_claim_bandwidth (struct usb_device * dev, struct urb * urb,
int bustime, int isoc);
ARGUMENTS
dev source/target of request
urb request (urb->dev == dev)
bustime
bandwidth consumed, in (average) microseconds per frame
isoc true iff the request is isochronous
DESCRIPTION
Bus bandwidth reservations are recorded purely for diagnostic purposes.
HCDs are expected not to overcommit periodic bandwidth, and to record
such reservations whenever endpoints are added to the periodic
schedule.
FIXME averaging per-frame is suboptimal. Better to sum over the HCD’s
entire periodic schedule ... 32 frames for OHCI, 1024 for UHCI,
settable for EHCI (256/512/1024 frames, default 1024) and have the bus
expose how large its periodic schedule is.