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

From: [email-masked] (Marc Zyngier)
Date: Mon, 24 Mar 2014 11:10:48 +0000

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 <[email-masked]
> <mailto:[email-masked]>> 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...