[PATCH v2 02/19] arm64: initial support for GICv3

Hi Zi,

On 22/03/14 01:21, Zi Shen Lim wrote:

Hi Marc,

On Thu, Mar 20, 2014 at 4:52 AM, Marc Zyngier <marc.zyngier@arm.com
<mailto:marc.zyngier@arm.com>> wrote:
<snip>
 

    +       /*
    +        * Find out how many interrupts are supported.
    +        * The GIC only supports up to 1020 interrupt sources
    (SGI+PPI+SPI)
    +        */
    +       gic_irqs = readl_relaxed(gic_data.dist_base + GICD_TYPER) &
    0x1f;
    +       gic_irqs = (gic_irqs + 1) * 32;
    +       if (gic_irqs > 1020)
    +               gic_irqs = 1020;
    +       gic_data.irq_nr = gic_irqs;
    +
    +       gic_data.domain = irq_domain_add_linear(node, gic_irqs - 16,
    +                                               &gic_irq_domain_ops,
    &gic_data);


Why gic_irqs - 16?

Because we keep the SGIs (all 16 of them) for the core kernel (drivers
are not allowed to request them).

    __irq_domain_add(of_node, size, size, 0, ops, host_data);

        domain->hwirq_max = hwirq_max;


So hwirq_max is effectively set to actual_hwirq_max-16.

Later, the following warning can be triggered:

    int irq_domain_associate(struct irq_domain *domain, unsigned int virq,
                             irq_hw_number_t hwirq)
    {
            struct irq_data *irq_data = irq_get_irq_data(virq);
            int ret;

            if (WARN(hwirq >= domain->hwirq_max,
                     "error: hwirq 0x%x is too large for %s\n",
    (int)hwirq, domain->name))
                    return -EINVAL;

Do you actually see this warning being triggered? I don't. We're using a
linear domain that doesn't call into this function.

What am I missing?

Cheers,

	M.
-- 
Jazz is not dead. It just smells funny...