usb_calc_bus_time
Prev | Chapter 6. Host Controller APIs | Next

## Name

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.

Prev | Up | Next
Chapter 6. Host Controller APIs | Home | usb_hcd_link_urb_to_ep