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SubjectRe: [PATCH v3 1/3] irqchip/loongson-eiointc: Skip handling if there is no pending irq
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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@loongson.cn> 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@loongson.cn>
>> ---
>> 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
>>


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