Re: [PATCH v4 2/3] irqchip/loongson-eiointc: Skip handling if there is no pending irq

[Huacai Chen]

Hi, Bibo,

As commented in another patch, you can use eiointc_irq_dispatch(),
iocsr_read64() to describe functions, and it is better to use
Loongson-3A5000, Loongson-2K2000, Loongson-2K0500 rather than 3A5000,
2K2000, 2K0500. Besides, please always use IRQs rather than IRQS.

With these modifications,

Acked-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>

On Thu, Jan 25, 2024 at 7:36 PM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
>
> It is one simple optimization in the interrupt dispatch function
> eiointc_irq_dispatch. There are 256 IRQs supported for eiointc on
> 3A5000 and 2K2000 platform, 128 IRQS on 2K0500 platform, eiointc irq
> handler reads the bitmap and find pending irqs when irq happens. So
> there are several consecutive iocsr_read64 operations for the all
> 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 | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
> index b3736bdd4b9f..6a71a8c29ac7 100644
> --- a/drivers/irqchip/irq-loongson-eiointc.c
> +++ b/drivers/irqchip/irq-loongson-eiointc.c
> @@ -198,6 +198,12 @@ 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));
> +
> +               /* Skip handling if pending bitmap is zero */
> +               if (!pending)
> +                       continue;
> +
> +               /* Clear the IRQs */
>                 iocsr_write64(pending, EIOINTC_REG_ISR + (i << 3));
>                 while (pending) {
>                         int bit = __ffs(pending);
> --
> 2.39.3
>