This is a note to let you know that I've just added the patch titled
serial/mxs-auart: fix race condition in interrupt handler
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-mxs-auart-fix-race-condition-in-interrupt-handler.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d970d7fe65adff5efe75b4a73c4ffc9be57089f7 Mon Sep 17 00:00:00 2001
From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Date: Thu, 4 Jul 2013 11:28:51 +0200
Subject: serial/mxs-auart: fix race condition in interrupt handler
From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/mxs-auart.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -375,11 +375,18 @@ static void mxs_auart_settermios(struct
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);
@@ -398,12 +405,6 @@ static irqreturn_t mxs_auart_irq_handle(
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;
}
Patches currently in stable-queue which might be from u.kleine-koenig@xxxxxxxxxxxxxx are
queue-3.4/serial-mxs-auart-increase-time-to-wait-for-transmitter-to-become-idle.patch
queue-3.4/serial-mxs-auart-fix-race-condition-in-interrupt-handler.patch
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