Messages in this thread Patch in this message | | | From | Paul Gortmaker <> | Subject | [34-longterm 092/196] serial/imx: read cts state only after acking cts change irq | Date | Mon, 12 Mar 2012 20:20:05 -0400 |
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From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. -------------------
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and acking the irq (USR1_RTSD) the last edge doesn't generate an irq and uart_handle_cts_change is called with a outdated value for cts.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)
[PG: file in drivers/serial not drivers/tty/serial in .34]
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> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- drivers/serial/imx.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c index eacb588..6d2028e 100644 --- a/drivers/serial/imx.c +++ b/drivers/serial/imx.c @@ -383,12 +383,13 @@ 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); -- 1.7.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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