parport_wait_peripheral — wait for status lines to change in 35ms
int parport_wait_peripheral ( | struct parport * port, |
| unsigned char mask, | |
unsigned char result); |
This function waits until the masked status lines have the
desired values, or until 35ms have elapsed (see IEEE 1284-1994
page 24 to 25 for why this value in particular is hardcoded).
The mask and result parameters are bitmasks, with the bits
defined by the constants in parport.h: PARPORT_STATUS_BUSY,
and so on.
The port is polled quickly to start off with, in anticipation
of a fast response from the peripheral. This fast polling
time is configurable (using /proc), and defaults to 500usec.
If the timeout for this port (see parport_set_timeout) is
zero, the fast polling time is 35ms, and this function does
not call schedule.
If the timeout for this port is non-zero, after the fast
polling fails it uses parport_wait_event to wait for up to
10ms, waking up if an interrupt occurs.