usb_calc_bus_time (9)

Approximate periodic transaction time in nanoseconds

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  4. usb_calc_bus_time: Approximate periodic transaction time in nanoseconds
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  3. linux-manual-3.16
  4. 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.

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