Hi Felipe,
On Tuesday 08 December 2015 07:15 PM, Felipe Balbi wrote:
> Sekhar Nori <nsekhar@xxxxxx> writes:
>> + /*
>> + * A spurious IRQ can result if interrupt that triggered the
>> + * sorting is no longer active during the sorting (10 INTC
>> + * functional clock cycles after interrupt assertion). Or a
>> + * change in interrupt mask affected the result during sorting
>> + * time. There is no special handling required except ignoring
>> + * the SIR register value just read and retrying.
>> + * See section 6.2.5 of AM335x TRM Literature Number: SPRUH73K
>> + *
>> + * Many a times, a spurious interrupt situation has been fixed
>> + * by adding a flush for the posted write acking the IRQ in
>> + * the device driver. Typically, this is going be the device
>> + * driver whose interrupt was handled just before the spurious
>> + * IRQ occurred. Pay attention to those device drivers if you
>> + * run into hitting the spurious IRQ condition below.
>> + */
>> + if ((irqnr & SPURIOUSIRQ_MASK) == SPURIOUSIRQ_MASK) {
>
> sounds like unlikely() wouldn't hurt here.
I can add, but looks like it does not make a big difference. See below.
>
>> + pr_err_once("%s: spurious irq!\n", __func__);
>> + irq_err_count++;
>> + omap_ack_irq(NULL);
>> + return;
>> + }
>> +
>> irqnr &= ACTIVEIRQ_MASK;
>> - WARN_ONCE(!irqnr, "Spurious IRQ ?\n");
>> handle_domain_irq(domain, irqnr, regs);
>
> care to run kernel function profiler against omap_intc_handle_irq()
> before and after this patch ?
Before this patch I see average running time time of 34us. That
increases to 37.8us after this patch. With unlikely() the number I got
was 37.4us. So the benefit with unlikely() is in the noise range.
This was using AM335x EVM at 720 MHz.
Thanks,
Sekhar
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