[PATCH] mfd: arizona: Check if AOD interrupts are pending before dispatching

[PATCH] mfd: arizona: Check if AOD interrupts are pending before dispatching

[Richard Fitzgerald]

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>
---
 drivers/mfd/arizona-irq.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/mfd/arizona-irq.c b/drivers/mfd/arizona-irq.c
index edeb495..edaf592 100644
--- a/drivers/mfd/arizona-irq.c
+++ b/drivers/mfd/arizona-irq.c
@@ -97,7 +97,7 @@ static irqreturn_t arizona_irq_thread(int irq, void *data)
 {
 	struct arizona *arizona = data;
 	bool poll;
-	unsigned int val;
+	unsigned int val, nest_irq;
 	int ret;
 
 	ret = pm_runtime_get_sync(arizona->dev);
@@ -109,8 +109,23 @@ 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 == 0 && val != 0) {
+				nest_irq = irq_find_mapping(arizona->virq, 0);
+				handle_nested_irq(nest_irq);
+			} else if (ret != 0) {
+				dev_err(arizona->dev,
+					"Failed to read AOD IRQ1 %d\n",
+					ret);
+			}
+		}
 
 		/*
 		 * Check if one of the main interrupts is asserted and only
-- 
1.9.1

Re: [PATCH] mfd: arizona: Check if AOD interrupts are pending before dispatching

[Lee Jones]

On Thu, 14 Apr 2016, Richard Fitzgerald wrote:

> 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>
> ---
>  drivers/mfd/arizona-irq.c | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mfd/arizona-irq.c b/drivers/mfd/arizona-irq.c
> index edeb495..edaf592 100644
> --- a/drivers/mfd/arizona-irq.c
> +++ b/drivers/mfd/arizona-irq.c
> @@ -97,7 +97,7 @@ static irqreturn_t arizona_irq_thread(int irq, void *data)
>  {
>  	struct arizona *arizona = data;
>  	bool poll;
> -	unsigned int val;
> +	unsigned int val, nest_irq;
>  	int ret;
>  
>  	ret = pm_runtime_get_sync(arizona->dev);
> @@ -109,8 +109,23 @@ 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);

Nit: Pop this on the line above.

> +			if (ret == 0 && val != 0) {
> +				nest_irq = irq_find_mapping(arizona->virq, 0);
> +				handle_nested_irq(nest_irq);
> +			} else if (ret != 0) {
> +				dev_err(arizona->dev,

It's only a valid 'error' if you're return an error condition.
AFAICT, you're not doing that, so use dev_warn() instead.

> +					"Failed to read AOD IRQ1 %d\n",
> +					ret);

Nit: Pop this on the line above.

> +			}
> +		}

I think the whole thing would be better written like:

		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

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
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