diff options
authorUwe Kleine-König <u.kleine-koenig@pengutronix.de>2011-04-11 10:59:09 +0200
committerEric Miao <eric.miao@canonical.com>2011-11-10 07:39:02 +0800
commit3295abd7d6ccacd8d37a6f4d9b14c134b2cb3554 (patch)
parente7ae1fa71713c98625a9dfac084ae7a3548c4e8b (diff)
serial/imx: read cts state only after acking cts change irq
commit 5680e94148a86e8c31fdc5cb0ea0d5c6810c05b0 upstream. 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and acking the irq (USR1_RTSD) the last edge doesn't generate an irq and uart_handle_cts_change is called with a outdated value for cts.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@de.trumpf.com> Tested-by: Arwed Springer <Arwed.Springer@de.trumpf.com> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> (cherry picked from commit 1eb710f4e01a9afab735828c87ef13e2e6b57386)
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 21516c8fa03..531d442415b 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);