irqchip/loongson-eiointc: Refine irq affinity setting during resume

  During suspend and resume, other CPUs are removed and IRQs are migrated
to CPU0. So it is not necessary to restore irq affinity for eiointc.

Also there is some optimization for function eiointc_irq_dispatch,
in genral there are 256 IRQs supported for eiointc. When irq happens,
eiointc irq handler reads the bitmap and find pending irqs. There are
4 times of  consecutive iocsr_read64 operations for the total 256 bits,
indeed in most scenario pending value is zero in 3 times, and not zero
in one time. Here zero checking is added to avoid some useless
operations sush as clearing hw ISR.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
---
 drivers/irqchip/irq-loongson-eiointc.c | 29 +++++++++++---------------
 1 file changed, 12 insertions(+), 17 deletions(-)
  

+ irqchip maintainer Thomas.

Jianmin,

Could you give some feedback about this patch since you are author about 
this patch? By searching code of all hw irqchip drivers, there is no 
affinity restoring during s3/s4.

Regards
Bibo Mao

On 2023/12/19 下午5:51, Bibo Mao wrote:
> During suspend and resume, other CPUs are removed and IRQs are migrated
> to CPU0. So it is not necessary to restore irq affinity for eiointc.
> 
> Also there is some optimization for function eiointc_irq_dispatch,
> in genral there are 256 IRQs supported for eiointc. When irq happens,
> eiointc irq handler reads the bitmap and find pending irqs. There are
> 4 times of  consecutive iocsr_read64 operations for the total 256 bits,
> indeed in most scenario pending value is zero in 3 times, and not zero
> in one time. Here zero checking is added to avoid some useless
> operations sush as clearing hw ISR.
> 
> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
> ---
>   drivers/irqchip/irq-loongson-eiointc.c | 29 +++++++++++---------------
>   1 file changed, 12 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
> index 1623cd779175..b01be85b8ebc 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.
> +		 *
> +		 * In most scenario value of pending is 0 if no multiple IRQs
> +		 * happen at the same time
> +		 */
> +		if (!pending)
> +			continue;
> +
>   		iocsr_write64(pending, EIOINTC_REG_ISR + (i << 3));
>   		while (pending) {
>   			int bit = __ffs(pending);
> @@ -241,7 +252,7 @@ static int eiointc_domain_alloc(struct irq_domain *domain, unsigned int virq,
>   	int ret;
>   	unsigned int i, type;
>   	unsigned long hwirq = 0;
> -	struct eiointc *priv = domain->host_data;
> +	struct eiointc_priv *priv = domain->host_data;
>   
>   	ret = irq_domain_translate_onecell(domain, arg, &hwirq, &type);
>   	if (ret)
> @@ -304,23 +315,7 @@ static int eiointc_suspend(void)
>   
>   static void eiointc_resume(void)
>   {
> -	int i, j;
> -	struct irq_desc *desc;
> -	struct irq_data *irq_data;
> -
>   	eiointc_router_init(0);
> -
> -	for (i = 0; i < nr_pics; i++) {
> -		for (j = 0; j < eiointc_priv[0]->vec_count; j++) {
> -			desc = irq_resolve_mapping(eiointc_priv[i]->eiointc_domain, j);
> -			if (desc && desc->handle_irq && desc->handle_irq != handle_bad_irq) {
> -				raw_spin_lock(&desc->lock);
> -				irq_data = irq_domain_get_irq_data(eiointc_priv[i]->eiointc_domain, irq_desc_get_irq(desc));
> -				eiointc_set_irq_affinity(irq_data, irq_data->common->affinity, 0);
> -				raw_spin_unlock(&desc->lock);
> -			}
> -		}
> -	}
>   }
>   
>   static struct syscore_ops eiointc_syscore_ops = {
>
  

> -----Original Messages-----
> From: maobibo <maobibo@loongson.cn>
> Send time:Thursday, 01/04/2024 15:53:51
> To: "Huacai Chen" <chenhuacai@kernel.org>, "Jiaxun Yang" <jiaxun.yang@flygoat.com>, "Thomas Gleixner" <tglx@linutronix.de>
> Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, "Jianmin Lv" <lvjianmin@loongson.cn>
> Subject: Re: [PATCH] irqchip/loongson-eiointc: Refine irq affinity setting during resume
> 
> + irqchip maintainer Thomas.
> 
> Jianmin,
> 
> Could you give some feedback about this patch since you are author about 
> this patch? By searching code of all hw irqchip drivers, there is no 
> affinity restoring during s3/s4.
> 
> Regards
> Bibo Mao
> 

Hi, bibo

I looked into the patch, IMO, the change here in your patch is reasonable. The original restoring code here
is aimed to restore irq routing registers from its' affinity, but it seems that the affinity
may be changed during cpu offline, so we should not use it this way. Moreover, the affinity of each irq will
be set to boot cpu after all of non-boot cpus are offline before suspend callback, so it seems that affinity
restoring is not needed.
 
> On 2023/12/19 下午5:51, Bibo Mao wrote:
> > During suspend and resume, other CPUs are removed and IRQs are migrated
> > to CPU0. So it is not necessary to restore irq affinity for eiointc.
> > 
> > Also there is some optimization for function eiointc_irq_dispatch,
> > in genral there are 256 IRQs supported for eiointc. When irq happens,
> > eiointc irq handler reads the bitmap and find pending irqs. There are
> > 4 times of  consecutive iocsr_read64 operations for the total 256 bits,
> > indeed in most scenario pending value is zero in 3 times, and not zero
> > in one time. Here zero checking is added to avoid some useless
> > operations sush as clearing hw ISR.
> > 
> > Signed-off-by: Bibo Mao <maobibo@loongson.cn>
> > ---
> >   drivers/irqchip/irq-loongson-eiointc.c | 29 +++++++++++---------------
> >   1 file changed, 12 insertions(+), 17 deletions(-)
> > 
> > diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
> > index 1623cd779175..b01be85b8ebc 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.
> > +		 *
> > +		 * In most scenario value of pending is 0 if no multiple IRQs
> > +		 * happen at the same time
> > +		 */
> > +		if (!pending)
> > +			continue;
> > +
> >   		iocsr_write64(pending, EIOINTC_REG_ISR + (i << 3));
> >   		while (pending) {
> >   			int bit = __ffs(pending);
> > @@ -241,7 +252,7 @@ static int eiointc_domain_alloc(struct irq_domain *domain, unsigned int virq,
> >   	int ret;
> >   	unsigned int i, type;
> >   	unsigned long hwirq = 0;
> > -	struct eiointc *priv = domain->host_data;
> > +	struct eiointc_priv *priv = domain->host_data;
> >   
> >   	ret = irq_domain_translate_onecell(domain, arg, &hwirq, &type);
> >   	if (ret)
> > @@ -304,23 +315,7 @@ static int eiointc_suspend(void)
> >   
> >   static void eiointc_resume(void)
> >   {
> > -	int i, j;
> > -	struct irq_desc *desc;
> > -	struct irq_data *irq_data;
> > -
> >   	eiointc_router_init(0);
> > -
> > -	for (i = 0; i < nr_pics; i++) {
> > -		for (j = 0; j < eiointc_priv[0]->vec_count; j++) {
> > -			desc = irq_resolve_mapping(eiointc_priv[i]->eiointc_domain, j);
> > -			if (desc && desc->handle_irq && desc->handle_irq != handle_bad_irq) {
> > -				raw_spin_lock(&desc->lock);
> > -				irq_data = irq_domain_get_irq_data(eiointc_priv[i]->eiointc_domain, irq_desc_get_irq(desc));
> > -				eiointc_set_irq_affinity(irq_data, irq_data->common->affinity, 0);
> > -				raw_spin_unlock(&desc->lock);
> > -			}
> > -		}
> > -	}
> >   }
> >   
> >   static struct syscore_ops eiointc_syscore_ops = {
> > 


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