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[SERIAL] Fix clocal wakeup problem 

Jim Alexander reported a problem where "if one calls open() in
blocking mode with CLOCAL off, the 8250.c driver under the 2.6
kernel (or at least 2.6.8 and 2.6.10) does not wake up the
blocked process when DCD is asserted."

Fix this by enabling modem status interrupts immediately before
we read the carrier detect status.

Thanks to Jim for reporting the problem and testing the fix.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2006-01-07 23:11:23 +00:00 committed by Russell King
parent b9abaa3fb7
commit f61051cd2f
1 changed files with 1 additions and 0 deletions
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1
drivers/serial/serial_core.c
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@ -1440,6 +1440,7 @@ uart_block_til_ready(struct file *filp, struct uart_state *state)
* modem is ready for us.
*/
spin_lock_irq(&port->lock);
port->ops->enable_ms(port);
mctrl = port->ops->get_mctrl(port);
spin_unlock_irq(&port->lock);
if (mctrl & TIOCM_CAR)