Re: [PATCH net] dsa: mv88e6xxx: Ensure all pending interrupts are handled prior to exit

[Andrew Lunn]

> Signed-off-by:  John David Anglin <dave.ang...@bell.net>
> ---
>  drivers/net/dsa/mv88e6xxx/chip.c | 28 ++++++++++++++++++++++------
>  1 file changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/dsa/mv88e6xxx/chip.c 
> b/drivers/net/dsa/mv88e6xxx/chip.c
> index 8dca2c949e73..12fd7ce3f1ff 100644
> --- a/drivers/net/dsa/mv88e6xxx/chip.c
> +++ b/drivers/net/dsa/mv88e6xxx/chip.c
> @@ -261,6 +261,7 @@ static irqreturn_t mv88e6xxx_g1_irq_thread_work(struct 
> mv88e6xxx_chip *chip)
>       unsigned int sub_irq;
>       unsigned int n;
>       u16 reg;
> +     u16 ctl1;
>       int err;
> 
>       mutex_lock(&chip->reg_lock);
> @@ -270,13 +271,28 @@ static irqreturn_t mv88e6xxx_g1_irq_thread_work(struct 
> mv88e6xxx_chip *chip)
>       if (err)
>               goto out;
> 
> -     for (n = 0; n < chip->g1_irq.nirqs; ++n) {
> -             if (reg & (1 << n)) {
> -                     sub_irq = irq_find_mapping(chip->g1_irq.domain, n);
> -                     handle_nested_irq(sub_irq);
> -                     ++nhandled;
> +     do {
> +             for (n = 0; n < chip->g1_irq.nirqs; ++n) {
> +                     if (reg & (1 << n)) {
> +                             sub_irq = irq_find_mapping(chip->g1_irq.domain,
> +                                                        n);
> +                             handle_nested_irq(sub_irq);
> +                             ++nhandled;
> +                     }
>               }
> -     }
> +
> +             mutex_lock(&chip->reg_lock);
> +             err = mv88e6xxx_g1_read(chip, MV88E6XXX_G1_CTL1, &ctl1);
> +             if (err)
> +                     goto unlock;
> +             err = mv88e6xxx_g1_read(chip, MV88E6XXX_G1_STS, &reg);
> +unlock:
> +             mutex_unlock(&chip->reg_lock);
> +             if (err)
> +                     goto out;
> +             ctl1 &= GENMASK(chip->g1_irq.nirqs, 0);
> +     } while (reg & ctl1);

Hi David

I just tested this on one of my boards. It loops endlessly:

[   47.173396] mv88e6xxx_g1_irq_thread_work: c881 a8 80                         
[   47.182108] mv88e6xxx_g1_irq_thread_work: c881 a8 80                         
[   47.190820] mv88e6xxx_g1_irq_thread_work: c881 a8 80                         
[   47.199535] mv88e6xxx_g1_irq_thread_work: c881 a8 80                         
[   47.208254] mv88e6xxx_g1_irq_thread_work: c881 a8 80   

These are reg, ctl1, reg & ctl1.

So there is an unhandled device interrupt. I think this is because
device interrupts are not masked before installing the interrupt
handler. But i've not fully got to the bottom of this yet.

         Andrew