On Fri, Jul 15, 2016 at 05:44:50PM +0800, Wan ZongShun wrote:

2016-07-15 15:00 GMT+08:00 Arnd Bergmann [off-list ref]:

quoted

On Friday, July 15, 2016 1:15:58 PM CEST Wan Zongshun wrote:

quoted

Actually, I have two choice to implement this function:

option1:

void __exception_irq_entry aic_handle_irq(struct pt_regs *regs)
{
        u32 hwirq;

        (void)readl(aic_base + REG_AIC_IPER);
        hwirq = readl(aic_base + REG_AIC_ISNR);

        handle_IRQ((irq_find_mapping(aic_domain, hwirq)), regs);
}

(side note: I think you want handle_domain_irq())

quoted

option2:

void __exception_irq_entry aic_handle_irq(struct pt_regs *regs)
{
        u32 hwirq;

        hwirq = readl(aic_base + REG_AIC_IPER);
        hwirq <<= 2;

        handle_IRQ((irq_find_mapping(aic_domain, hwirq)), regs);
}

Though the option2 do shift for hwirq, but it seems better than do io
operation by readl,so I prefer to option2, agree?

That will only return an irq number that is a multiple of four, which
seems wrong since the numbers are not that. Did you mean to write

        hwirq = ilog2(hwirq);   ?

Sorry, my fault, I mean hwirq >>= 2, bit[7:2] indicates which irq is triggering.
so I have to do right shift 2 for IPER value.

Ok, this makes a lot more sense now. :)

quoted

That assumes that REG_AIC_IPER contains a 32-bit value with one single
bit set to indicate which IRQ was triggered.

If the difference is only in performance, you could try measuring which
of the two ends up being faster.

It seems hard to measure. I think Do IO operation should be slower
than shift 2. :)

Agreed.

thx,

Jason.