pinctrl: ocelot: fix system hang on level based interrupts

commit 93b8ddc54507a227087c60a0013ed833b6ae7d3c upstream.

The current implementation only calls chained_irq_enter() and
chained_irq_exit() if it detects pending interrupts.

```
for (i = 0; i < info->stride; i++) {
	uregmap_read(info->map, id_reg + 4 * i, &reg);
	if (!reg)
		continue;

	chained_irq_enter(parent_chip, desc);
```

However, in case of GPIO pin configured in level mode and the parent
controller configured in edge mode, GPIO interrupt might be lowered by the
hardware. In the result, if the interrupt is short enough, the parent
interrupt is still pending while the GPIO interrupt is cleared;
chained_irq_enter() never gets called and the system hangs trying to
service the parent interrupt.

Moving chained_irq_enter() and chained_irq_exit() outside the for loop
ensures that they are called even when GPIO interrupt is lowered by the
hardware.

The similar code with chained_irq_enter() / chained_irq_exit() functions
wrapping interrupt checking loop may be found in many other drivers:
```
grep -r -A 10 chained_irq_enter drivers/pinctrl
```

Cc: stable@vger.kernel.org
Signed-off-by: Sergey Matsievskiy <matsievskiysv@gmail.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/20241012105743.12450-2-matsievskiysv@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/pinctrl/pinctrl-ocelot.c b/drivers/pinctrl/pinctrl-ocelot.c
index b14f1b7a625ec281da2451b43e2780c408affa55..9f1b88fa33b47dd2add506d5c1ae8b5738fa420d 100644 (file)
--- a/drivers/pinctrl/pinctrl-ocelot.c
+++ b/drivers/pinctrl/pinctrl-ocelot.c
@@ -1279,21 +1279,21 @@ static void ocelot_irq_handler(struct irq_desc *desc)
        unsigned int reg = 0, irq, i;
        unsigned long irqs;
 
+       chained_irq_enter(parent_chip, desc);
+
        for (i = 0; i < info->stride; i++) {
                regmap_read(info->map, id_reg + 4 * i, &reg);
                if (!reg)
                        continue;
 
-               chained_irq_enter(parent_chip, desc);
-
                irqs = reg;
 
                for_each_set_bit(irq, &irqs,
                                 min(32U, info->desc->npins - 32 * i))
                        generic_handle_domain_irq(chip->irq.domain, irq + 32 * i);
-
-               chained_irq_exit(parent_chip, desc);
        }
+
+       chained_irq_exit(parent_chip, desc);
 }
 
 static int ocelot_gpiochip_register(struct platform_device *pdev,