Commit 5680e941 authored Apr 11, 2011 by Uwe Kleine-König Committed by Greg Kroah-Hartman Apr 19, 2011

serial/imx: read cts state only after acking cts change irq



If cts changes between reading the level at the cts input (USR1_RTSS)
and acking the irq (USR1_RTSD) the last edge doesn't generate an irq and
uart_handle_cts_change is called with a outdated value for cts.

The race was introduced by commit

	ceca629e ([ARM] 2971/1: i.MX uart handle rts irq)

Reported-by: Arwed Springer <Arwed.Springer@de.trumpf.com>
Tested-by: Arwed Springer <Arwed.Springer@de.trumpf.com>
Cc: stable@kernel.org # 2.6.14+
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent 0f6db217

drivers/tty/serial/imx.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -382,12 +382,13 @@ static void imx_start_tx(struct uart_port *port)
		static irqreturn_t imx_rtsint(int irq, void *dev_id)
		{
		struct imx_port *sport = dev_id;
		unsigned int val = readl(sport->port.membase + USR1) & USR1_RTSS;
		unsigned int val;
		unsigned long flags;

		spin_lock_irqsave(&sport->port.lock, flags);

		writel(USR1_RTSD, sport->port.membase + USR1);
		val = readl(sport->port.membase + USR1) & USR1_RTSS;
		uart_handle_cts_change(&sport->port, !!val);
		wake_up_interruptible(&sport->port.state->port.delta_msr_wait);

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