Re: [PATCH v3 1/3] irqchip/loongson-eiointc: Skip handling if there is no pending irq

[maobibo]

On 2024/1/24 下午5:51, Huacai Chen wrote:
> Hi, Bibo,
>
> On Thu, Jan 18, 2024 at 8:15 PM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
> > There is one simple optimization in the interrupt dispatch function
> > eiointc_irq_dispatch. There are 256 IRQs supported for eiointc, eiointc
> > irq handler reads the bitmap and find pending irqs when irq happens.
> > So there are four times of consecutive iocsr_read64 operations for the
> > total 256 bits to find all pending irqs. If the pending bitmap is zero,
> > it means that there is no pending irq for the this irq bitmap range,
> > we can skip handling to avoid some useless operations such as clearing
> > hw ISR.
> >
> > Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> > ---
> >   drivers/irqchip/irq-loongson-eiointc.c | 11 +++++++++++
> >   1 file changed, 11 insertions(+)
> >
> > diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
> > index 1623cd779175..6143adb1b73b 100644
> > --- a/drivers/irqchip/irq-loongson-eiointc.c
> > +++ b/drivers/irqchip/irq-loongson-eiointc.c
> > @@ -198,6 +198,17 @@ static void eiointc_irq_dispatch(struct irq_desc *desc)
> >
> >          for (i = 0; i < eiointc_priv[0]->vec_count / VEC_COUNT_PER_REG; i++) {
> >                  pending = iocsr_read64(EIOINTC_REG_ISR + (i << 3));
> > +
> > +               /*
> > +                * Get pending eiointc irq from bitmap status, there are 4 times
> > +                * consecutive iocsr_read64 operations for 256 IRQs.
> > +                *
> > +                * Skip handling if pending bitmap is zero
> This driver is shared by Loongson-2 and Loongson-3 series, for
> Loongson-2K0500 there is only 128 IRQs, so I suggest only keep the
> last line "Skip handling if current pending bitmap is zero" is enough.
Sure, will refine the patch in this way.

Regards
Bibo Mao
> Huacai
>
> > +                */
> > +               if (!pending)
> > +                       continue;
> > +
> > +               /* Clear the IRQs */
> >                  iocsr_write64(pending, EIOINTC_REG_ISR + (i << 3));
> >                  while (pending) {
> >                          int bit = __ffs(pending);
> > --
> > 2.39.3