usb_calc_bus_time (9) Linux Manual Page
usb_calc_bus_time – approximate periodic transaction time in nanoseconds
Synopsis
long usb_calc_bus_time(int speed, int is_input, int isoc, int bytecount);Arguments
speed
-
- from dev->speed; USB_SPEED_{LOW,FULL,HIGH}
is_input
- true iff the transaction sends data to the host
isoc
- true for isochronous transactions, false for interrupt ones
bytecount
- how many bytes in the transaction.
Return
Approximate bus time in nanoseconds for a periodic transaction.
Note
See USB 2.0 spec section 5.11.3; only periodic transfers need to be scheduled in software, this function is only used for such scheduling.