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tty: Implement a drain delay in the tty port

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We need this for devices that cannot flush and wait, but which do not order
data and modem events. Without it we will hang up before all the data
clears the hardware. Needed for the USB changes.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alan Cox 2009-06-11 12:25:25 +01:00 committed by Linus Torvalds
parent fcc8ac1825
commit 1ec739be75
2 changed files with 14 additions and 0 deletions
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11
drivers/char/tty_port.c
View file

@ -308,6 +308,17 @@ int tty_port_close_start(struct tty_port *port, struct tty_struct *tty, struct f
if (port->flags & ASYNC_INITIALIZED &&
port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
tty_wait_until_sent(tty, port->closing_wait);
if (port->drain_delay) {
unsigned int bps = tty_get_baud_rate(tty);
long timeout;
if (bps > 1200)
timeout = max_t(long, (HZ * 10 * port->drain_delay) / bps,
HZ / 10);
else
timeout = 2 * HZ;
schedule_timeout_interruptible(timeout);
}
return 1;
}
EXPORT_SYMBOL(tty_port_close_start);

3
include/linux/tty.h
View file

@ -201,6 +201,9 @@ struct tty_port {
unsigned char *xmit_buf; /* Optional buffer */
int close_delay; /* Close port delay */
int closing_wait; /* Delay for output */
int drain_delay; /* Set to zero if no pure time
based drain is needed else
set to size of fifo */
};
/*