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