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[PATCH] Serial: Check status of CTS when using flow control 

Fix bugme #4712: read the CTS status and set hw_stopped if CTS
is not active when opening the port and/or enabling CRTSCTS

Thanks to Stefan Wolff for spotting this problem.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2005-06-29 18:40:53 +01:00 committed by Russell King
parent c5f4644e6c
commit 0dd7a1aed7
1 changed files with 17 additions and 0 deletions
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17
drivers/serial/serial_core.c
View File

@ -182,6 +182,13 @@ static int uart_startup(struct uart_state *state, int init_hw)
uart_set_mctrl(port, TIOCM_RTS | TIOCM_DTR);
}
if (info->flags & UIF_CTS_FLOW) {
spin_lock_irq(&port->lock);
if (!(port->ops->get_mctrl(port) & TIOCM_CTS))
info->tty->hw_stopped = 1;
spin_unlock_irq(&port->lock);
}
info->flags |= UIF_INITIALIZED;
clear_bit(TTY_IO_ERROR, &info->tty->flags);
@ -1134,6 +1141,16 @@ static void uart_set_termios(struct tty_struct *tty, struct termios *old_termios
spin_unlock_irqrestore(&state->port->lock, flags);
}
/* Handle turning on CRTSCTS */
if (!(old_termios->c_cflag & CRTSCTS) && (cflag & CRTSCTS)) {
spin_lock_irqsave(&state->port->lock, flags);
if (!(state->port->ops->get_mctrl(state->port) & TIOCM_CTS)) {
tty->hw_stopped = 1;
state->port->ops->stop_tx(state->port, 0);
}
spin_unlock_irqrestore(&state->port->lock, flags);
}
#if 0
/*
* No need to wake up processes in open wait, since they