media: st_rc: Don't stay on an IRQ handler forever

As warned by smatch:
	drivers/media/rc/st_rc.c:110 st_rc_rx_interrupt() warn: this loop depends on readl() succeeding

If something goes wrong at readl(), the logic will stay there
inside an IRQ code forever. This is not the nicest thing to
do :-)

So, add a timeout there, preventing staying inside the IRQ
for more than 10ms.

Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/rc/st_rc.c

@@ -96,19 +96,24 @@ static void st_rc_send_lirc_timeout(struct rc_dev *rdev)
 
 static irqreturn_t st_rc_rx_interrupt(int irq, void *data)
 {
+	unsigned long timeout;
 	unsigned int symbol, mark = 0;
 	struct st_rc_device *dev = data;
 	int last_symbol = 0;
-	u32 status;
+	u32 status, int_status;
 	DEFINE_IR_RAW_EVENT(ev);
 
 	if (dev->irq_wake)
 		pm_wakeup_event(dev->dev, 0);
 
-	status  = readl(dev->rx_base + IRB_RX_STATUS);
+	/* FIXME: is 10ms good enough ? */
+	timeout = jiffies +  msecs_to_jiffies(10);
+	do {
+		status  = readl(dev->rx_base + IRB_RX_STATUS);
+		if (!(status & (IRB_FIFO_NOT_EMPTY | IRB_OVERFLOW)))
+			break;
 
-	while (status & (IRB_FIFO_NOT_EMPTY | IRB_OVERFLOW)) {
-		u32 int_status = readl(dev->rx_base + IRB_RX_INT_STATUS);
+		int_status = readl(dev->rx_base + IRB_RX_INT_STATUS);
 		if (unlikely(int_status & IRB_RX_OVERRUN_INT)) {
 			/* discard the entire collection in case of errors!  */
 			ir_raw_event_reset(dev->rdev);
@@ -148,8 +153,7 @@ static irqreturn_t st_rc_rx_interrupt(int irq, void *data)
 
 		}
 		last_symbol = 0;
-		status  = readl(dev->rx_base + IRB_RX_STATUS);
-	}
+	} while (time_is_after_jiffies(timeout));
 
 	writel(IRB_RX_INTS, dev->rx_base + IRB_RX_INT_CLEAR);