mfd: arizona: Check if AOD interrupts are pending before dispatching

Previously the arizona_irq_thread implementation would call
handle_nested_irqs() to handle AOD interrupts without checking if any
were actually pending. The kernel will see these as spurious IRQs and
will eventually disable the IRQ.

This patch ensures we only launch the nested handler if there are AOD
interrupts pending in the codec.

Signed-off-by: Simon Trimmer <simont@opensource.wolfsonmicro.com>
Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/arizona-irq.c

@@ -109,8 +109,20 @@ static irqreturn_t arizona_irq_thread(int irq, void *data)
 	do {
 		poll = false;
 
-		if (arizona->aod_irq_chip)
-			handle_nested_irq(irq_find_mapping(arizona->virq, 0));
+		if (arizona->aod_irq_chip) {
+			/*
+			 * Check the AOD status register to determine whether
+			 * the nested IRQ handler should be called.
+			 */
+			ret = regmap_read(arizona->regmap,
+					  ARIZONA_AOD_IRQ1, &val);
+			if (ret)
+				dev_warn(arizona->dev,
+					"Failed to read AOD IRQ1 %d\n", ret);
+			else if (val)
+				handle_nested_irq(
+					irq_find_mapping(arizona->virq, 0));
+		}
 
 		/*
 		 * Check if one of the main interrupts is asserted and only