[PATCH] i2c-rcar: check for no IRQ in rcar_i2c_irq()

[Sergei Shtylyov <sergei.shtylyov-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org>]

Check if the ICMSR register (masked with the ICMIER register) evaluates to 0  in
the driver's interrupt handler and return IRQ_NONE in that case, like many other
drivers do.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org>

---
The patch is against Wolfram Sang's 'linux.git' repo's 'i2c/for-next' branch
plus 3 cleanup patches just re-posted.

 drivers/i2c/busses/i2c-rcar.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Index: renesas/drivers/i2c/busses/i2c-rcar.c
===================================================================
--- renesas.orig/drivers/i2c/busses/i2c-rcar.c
+++ renesas/drivers/i2c/busses/i2c-rcar.c
@@ -361,6 +361,7 @@ static void rcar_i2c_irq_recv(struct rca
 static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
 {
 	struct rcar_i2c_priv *priv = ptr;
+	irqreturn_t result = IRQ_HANDLED;
 	u32 msr;
 
 	/*-------------- spin lock -----------------*/
@@ -370,6 +371,10 @@ static irqreturn_t rcar_i2c_irq(int irq,
 
 	/* Only handle interrupts that are currently enabled */
 	msr &= rcar_i2c_read(priv, ICMIER);
+	if (!msr) {
+		result = IRQ_NONE;
+		goto exit;
+	}
 
 	/* Arbitration lost */
 	if (msr & MAL) {
@@ -404,10 +409,11 @@ out:
 		wake_up(&priv->wait);
 	}
 
+exit:
 	spin_unlock(&priv->lock);
 	/*-------------- spin unlock -----------------*/
 
-	return IRQ_HANDLED;
+	return result;
 }
 
 static int rcar_i2c_master_xfer(struct i2c_adapter *adap,