On Mon, 20 Sep 2021 11:05:26 +0100,
Daniel Palmer [off-list ref] wrote:

Hi Marc,

On Mon, 20 Sept 2021 at 18:45, Marc Zyngier [off-list ref] wrote:

quoted

quoted

+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.

You may want to enable lockdep to verify that.

quoted

quoted

+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.

Then this doesn't work for edge signalling, as you will lose
interrupts that occur between the handling and EOI.

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.

That's probably because you are using the wrong flow handler. You
should turn this irq_eoi into an irq_ack, because that's really what
it is, and use handle_edge_irq() as the flow handler.

Thanks,

	M.

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

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