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authorUwe Kleine-König <u.kleine-koenig@pengutronix.de>2013-07-04 11:28:51 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-11 15:38:21 -0700
commit8c7e5916a54affa0565428f8926008f0d175ae88 (patch)
tree8ea0e33b083ec84bcf18fdb13118b4551a240b1e /drivers
parent83a5a29e61bc572110c0c4b8fc4e8d7838b8db53 (diff)
serial/mxs-auart: fix race condition in interrupt handler
commit d970d7fe65adff5efe75b4a73c4ffc9be57089f7 upstream. The handler needs to ack the pending events before actually handling them. Otherwise a new event might come in after it it considered non-pending or handled and is acked then without being handled. So this event is only noticed when the next interrupt happens. Without this patch an i.MX28 based machine running an rt-patched kernel regularly hangs during boot. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/tty/serial/mxs-auart.c17
1 files changed, 9 insertions, 8 deletions
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 5b3d063a4aa1..e6b8b09a7ef6 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -374,11 +374,18 @@ static void mxs_auart_settermios(struct uart_port *u,
static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
{
- u32 istatus, istat;
+ u32 istat;
struct mxs_auart_port *s = context;
u32 stat = readl(s->port.membase + AUART_STAT);
- istatus = istat = readl(s->port.membase + AUART_INTR);
+ istat = readl(s->port.membase + AUART_INTR);
+
+ /* ack irq */
+ writel(istat & (AUART_INTR_RTIS
+ | AUART_INTR_TXIS
+ | AUART_INTR_RXIS
+ | AUART_INTR_CTSMIS),
+ s->port.membase + AUART_INTR_CLR);
if (istat & AUART_INTR_CTSMIS) {
uart_handle_cts_change(&s->port, stat & AUART_STAT_CTS);
@@ -397,12 +404,6 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
istat &= ~AUART_INTR_TXIS;
}
- writel(istatus & (AUART_INTR_RTIS
- | AUART_INTR_TXIS
- | AUART_INTR_RXIS
- | AUART_INTR_CTSMIS),
- s->port.membase + AUART_INTR_CLR);
-
return IRQ_HANDLED;
}