[PATCH 2/3] irqchip: SigmaStar SSD20xD gpi

[Daniel Palmer]

Hi Marc,

On Mon, 20 Sept 2021 at 18:45, Marc Zyngier <maz at kernel.org> wrote:
> > +static void ssd20xd_gpi_unmask_irq(struct irq_data *data)
> > +{
> > +     irq_hw_number_t hwirq = irqd_to_hwirq(data);
> > +     struct ssd20xd_gpi *gpi = irq_data_get_irq_chip_data(data);
> > +     int offset_reg = REG_OFFSET(hwirq);
> > +     int offset_bit = BIT_OFFSET(hwirq);
> > +
> > +     regmap_update_bits(gpi->regmap, REG_MASK + offset_reg, offset_bit, 0);
>
> Is this regmap call atomic? When running this, you are holding a
> raw_spinlock already. From what I can see, this is unlikely to work
> correctly with the current state of regmap.

I didn't even think about it. I will check.

> > +static void ssd20x_gpi_chainedhandler(struct irq_desc *desc)
> > +{
> > +     struct ssd20xd_gpi *intc = irq_desc_get_handler_data(desc);
> > +     struct irq_chip *chip = irq_desc_get_chip(desc);
> > +     unsigned int irqbit, hwirq, virq, status;
> > +     int i;
> > +
> > +     chained_irq_enter(chip, desc);
> > +
> > +     for (i = 0; i < NUM_IRQ / IRQS_PER_REG; i++) {
> > +             int offset_reg = STRIDE * i;
> > +             int offset_irq = IRQS_PER_REG * i;
> > +
> > +             regmap_read(intc->regmap, REG_STATUS + offset_reg, &status);
>
> Does this act as an ACK in the HW?

Not that I'm aware of. The status registers have the interrupt bits
set until the EOI callback is called from what I can tell.
Technically I think the EOI callback should actually be ACK instead
but from my fuzzy memory with the stack of IRQ controllers that
resulted in a null pointer dereference.

> > +
> > +             while (status) {
> > +                     irqbit = __ffs(status);
> > +                     hwirq = offset_irq + irqbit;
> > +                     virq = irq_find_mapping(intc->domain, hwirq);
> > +                     if (virq)
> > +                             generic_handle_irq(virq);
>
> Please replace this with generic_handle_domain_irq().

Ok.

> > +IRQCHIP_DECLARE(ssd20xd_gpi, "sstar,ssd20xd-gpi", ssd20xd_gpi_of_init);
>
> Is there any reason why this isn't a standard platform device? In
> general, irqchips that are not part of the root hierarchy shouldn't
> need this anymore.

Nope. I can switch that over.

Cheers,

Daniel