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Commit 1ec739be authored Jun 11, 2009 by Alan Cox Committed by Linus Torvalds Jun 11, 2009

tty: Implement a drain delay in the tty port



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>

parent fcc8ac18

drivers/char/tty_port.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -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);

include/linux/tty.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -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 */
		};

		/*