[PATCH v2] i2c: exynos5: disable fifo-almost-empty irq signal when necessary

[Andrzej Hajda <a.hajda@samsung.com>]

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>
---
v2:
    - removed doubled conditional

 drivers/i2c/busses/i2c-exynos5.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
index bea6071..00e81e3 100644
--- a/drivers/i2c/busses/i2c-exynos5.c
+++ b/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++];
-- 
2.7.4