Re: [PATCH v2 1/1] pinctrl: ocelot: fix system hang on level based interrupts

[Linus Walleij]

On Sat, Oct 12, 2024 at 12:58 PM Sergey Matsievskiy
<matsievskiysv@xxxxxxxxx> wrote:

> 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
> ```
>
> Signed-off-by: Sergey Matsievskiy <matsievskiysv@xxxxxxxxx>
> Reviewed-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>

Patch applied and tagged for stable!

Yours,
Linus Walleij