Hi,
On Tue, Mar 11, 2014 at 04:51:00PM +0100, Hans de Goede wrote:
> SUN4I_IRQ_VECTOR_REG containing 0 can mean one of 2 things:
> 1) irq 0 pending
> 2) no more irqs pending
>
> So we must loop always atleast once to make irq 0 work, otherwise irq 0
> will never get serviced and we end up with a hard hang because
> sun4i_handle_irq gets re-entered constantly.
>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/irqchip/irq-sun4i.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/irqchip/irq-sun4i.c b/drivers/irqchip/irq-sun4i.c
> index a5438d8..3761bf1 100644
> --- a/drivers/irqchip/irq-sun4i.c
> +++ b/drivers/irqchip/irq-sun4i.c
> @@ -140,10 +140,16 @@ static asmlinkage void __exception_irq_entry sun4i_handle_irq(struct pt_regs *re
> {
> u32 irq, hwirq;
>
> + /*
> + * hwirq == 0 can mean one of 2 things:
> + * 1) irq 0 pending
> + * 2) no more irqs pending
3) spurious interrupt.
> + * So loop always atleast once to make irq 0 work.
> + */
> hwirq = readl(sun4i_irq_base + SUN4I_IRQ_VECTOR_REG) >> 2;
> - while (hwirq != 0) {
> + do {
I'd at least lookup in the pending register to see if the interrupt 0
was actually triggered. Otherwise, you could end up with spurious
handler calls on the interrupt 0.
> irq = irq_find_mapping(sun4i_irq_domain, hwirq);
> handle_IRQ(irq, regs);
> hwirq = readl(sun4i_irq_base + SUN4I_IRQ_VECTOR_REG) >> 2;
And you end up with the same issue if there's a first != 0 interrupt,
and then the interrupt 0.
What about something like:
while (1) {
hwirq = readl(sun4i_irq_base + SUN4I_IRQ_VECTOR_REG) >> 2;
if (!hwirq)
if (!(readl(sun4i_irq_base + SUN4I_IRQ_PENDING_REG(0)) & BIT(0)))
break;
irq = irq_find_mapping(sun4i_irq_domain, hwirq);
handle_IRQ(irq, regs);
}
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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