From d11699ef0bb1c2bcb7ba071ee129c2a59457053a Mon Sep 17 00:00:00 2001 From: Uwe Kleine-König Date: Thu, 4 Jul 2013 11:28:51 +0200 Subject: serial/mxs-auart: fix race condition in interrupt handler MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/mxs-auart.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c index 039c054349e..de42dd4ec52 100644 --- a/drivers/tty/serial/mxs-auart.c +++ b/drivers/tty/serial/mxs-auart.c @@ -375,11 +375,18 @@ 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); @@ -398,12 +405,6 @@ 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; } -- cgit v1.2.3-18-g5258