Re: [PATCH v4] irqchip/irq-mst: Support polarity configuration

[Marc Zyngier <maz@kernel.org>]

On Mon, 15 Mar 2021 13:18:48 +0000,
Mark-PK Tsai <mark-pk.tsai@mediatek.com> wrote:
> 
> Support irq polarity configuration and save and restore the config
> when system suspend and resume.
> 
> Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
> ---
>  drivers/irqchip/irq-mst-intc.c | 94 ++++++++++++++++++++++++++++++++--
>  1 file changed, 91 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-mst-intc.c b/drivers/irqchip/irq-mst-intc.c
> index 143657b0cf28..a2ab3f837b96 100644
> --- a/drivers/irqchip/irq-mst-intc.c
> +++ b/drivers/irqchip/irq-mst-intc.c
> @@ -13,15 +13,27 @@
>  #include <linux/of_irq.h>
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
> +#include <linux/syscore_ops.h>
>  
> -#define INTC_MASK	0x0
> -#define INTC_EOI	0x20
> +#define MST_INTC_MAX_IRQS	64
> +
> +#define INTC_MASK		0x0
> +#define INTC_REV_POLARITY	0x10
> +#define INTC_EOI		0x20
> +
> +#ifdef CONFIG_PM_SLEEP
> +static LIST_HEAD(mst_intc_list);
> +#endif
>  
>  struct mst_intc_chip_data {
>  	raw_spinlock_t	lock;
>  	unsigned int	irq_start, nr_irqs;
>  	void __iomem	*base;
>  	bool		no_eoi;
> +#ifdef CONFIG_PM_SLEEP
> +	struct list_head entry;
> +	u16 saved_polarity_conf[DIV_ROUND_UP(MST_INTC_MAX_IRQS, 16)];
> +#endif
>  };
>  
>  static void mst_set_irq(struct irq_data *d, u32 offset)
> @@ -78,6 +90,20 @@ static void mst_intc_eoi_irq(struct irq_data *d)
>  	irq_chip_eoi_parent(d);
>  }
>  
> +static int mst_irq_chip_set_type(struct irq_data *data, unsigned int type)
> +{
> +	if (type != IRQ_TYPE_EDGE_RISING && type != IRQ_TYPE_EDGE_FALLING &&
> +	    type != IRQ_TYPE_LEVEL_HIGH && type != IRQ_TYPE_LEVEL_LOW)
> +		return -EINVAL;

All of this amounts to checking for IRQ_TYPE_{NONE,EDGE_BOTH}. Maybe
that's a better option.

> +
> +	if (type == IRQ_TYPE_LEVEL_LOW || type == IRQ_TYPE_EDGE_FALLING)
> +		mst_set_irq(data, INTC_REV_POLARITY);

What happens if the interrupt was set to LEVEL_LOW, then switched to
LEVEL_HIGH? You end up with a stuck reversed polarity.

> +
> +	type = IRQ_TYPE_LEVEL_HIGH;
> +
> +	return irq_chip_set_type_parent(data, type);

I'm going to fix this as below. Shout if you disagree.

Thanks,

	M.

diff --git a/drivers/irqchip/irq-mst-intc.c b/drivers/irqchip/irq-mst-intc.c
index a2ab3f837b96..f6133ae28155 100644
--- a/drivers/irqchip/irq-mst-intc.c
+++ b/drivers/irqchip/irq-mst-intc.c
@@ -92,16 +92,20 @@ static void mst_intc_eoi_irq(struct irq_data *d)
 
 static int mst_irq_chip_set_type(struct irq_data *data, unsigned int type)
 {
-	if (type != IRQ_TYPE_EDGE_RISING && type != IRQ_TYPE_EDGE_FALLING &&
-	    type != IRQ_TYPE_LEVEL_HIGH && type != IRQ_TYPE_LEVEL_LOW)
-		return -EINVAL;
-
-	if (type == IRQ_TYPE_LEVEL_LOW || type == IRQ_TYPE_EDGE_FALLING)
+	switch (type) {
+	case IRQ_TYPE_LEVEL_LOW:
+	case IRQ_TYPE_EDGE_FALLING:
 		mst_set_irq(data, INTC_REV_POLARITY);
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+	case IRQ_TYPE_EDGE_RISING:
+		mst_clear_irq(data, INTC_REV_POLARITY);
+		break;
+	default:
+		return -EINVAL;
+	}
 
-	type = IRQ_TYPE_LEVEL_HIGH;
-
-	return irq_chip_set_type_parent(data, type);
+	return irq_chip_set_type_parent(data, IRQ_TYPE_LEVEL_HIGH);
 }
 
 static struct irq_chip mst_intc_chip = {

-- 
Without deviation from the norm, progress is not possible.