i2c: exynos5: disable fifo-almost-empty irq signal when necessary

Fifo-almost-empty irq signal should be disabled as soon as possible,
to avoid unnecessary interrupt storm. The best moment is when there is
no more data to feed fifo.
This patch fixes system stalls caused by IRQ storm.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Andi Shyti <andi.shyti@samsung.com>
Reviewed-by: Andi Shyti <andi.shyti@samsung.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-exynos5.c

@@ -502,8 +502,13 @@ static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id)
 		fifo_level = HSI2C_TX_FIFO_LVL(fifo_status);
 
 		len = i2c->variant->fifo_depth - fifo_level;
-		if (len > (i2c->msg->len - i2c->msg_ptr))
+		if (len > (i2c->msg->len - i2c->msg_ptr)) {
+			u32 int_en = readl(i2c->regs + HSI2C_INT_ENABLE);
+
+			int_en &= ~HSI2C_INT_TX_ALMOSTEMPTY_EN;
+			writel(int_en, i2c->regs + HSI2C_INT_ENABLE);
 			len = i2c->msg->len - i2c->msg_ptr;
+		}
 
 		while (len > 0) {
 			byte = i2c->msg->buf[i2c->msg_ptr++];