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uart_handle_cts_change is called with a outdated value for cts.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
ceca629 ([ARM] 2971/1: i.MX uart handle rts irq)
Reported-by: Arwed Springer <Arwed.Springer@xxxxxxxxxxxxx>
Tested-by: Arwed Springer <Arwed.Springer@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxx # 2.6.14+
Signed-off-by: Uwe Kleine-KÃnig <u.kleine-koenig@xxxxxxxxxxxxxx>
---
drivers/tty/serial/imx.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index dfcf4b1..0d66751 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -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);
--
1.7.2.3
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