Messages in this thread Patch in this message | | | Date | Fri, 29 Apr 2011 11:55:44 -0700 | From | Greg KH <> | Subject | [21/55] serial/imx: read cts state only after acking cts change irq |
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2.6.38-stable review patch. If anyone has any objections, please let us know.
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From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
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and acking the irq (USR1_RTSD) the last edge doesn't generate an irq and uart_handle_cts_change is called with a outdated value for cts.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>
--- drivers/tty/serial/imx.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -382,12 +382,13 @@ static void imx_start_tx(struct uart_por 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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