[PATCH v2] irqchip: LoongArch: Select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP

[PATCH v2] irqchip: LoongArch: Select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP

[Tiezhu Yang]

An IRQ's effective affinity can only be different from its configured
affinity if there are multiple CPUs. Make it clear that this option is
only meaningful when SMP is enabled.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---

v2: rebased on 6.1-rc2

 drivers/irqchip/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 7ef9f5e..8461915 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -575,7 +575,7 @@ config IRQ_LOONGARCH_CPU
 	bool
 	select GENERIC_IRQ_CHIP
 	select IRQ_DOMAIN
-	select GENERIC_IRQ_EFFECTIVE_AFF_MASK
+	select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
 	select LOONGSON_LIOINTC
 	select LOONGSON_EIOINTC
 	select LOONGSON_PCH_PIC
-- 
2.1.0

Re: [PATCH v2] irqchip: LoongArch: Select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP

[Marc Zyngier]

On Thu, 27 Oct 2022 04:39:09 +0100,
Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
> 
> An IRQ's effective affinity can only be different from its configured
> affinity if there are multiple CPUs. Make it clear that this option is
> only meaningful when SMP is enabled.
> 
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
> 
> v2: rebased on 6.1-rc2
> 
>  drivers/irqchip/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 7ef9f5e..8461915 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -575,7 +575,7 @@ config IRQ_LOONGARCH_CPU
>  	bool
>  	select GENERIC_IRQ_CHIP
>  	select IRQ_DOMAIN
> -	select GENERIC_IRQ_EFFECTIVE_AFF_MASK
> +	select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
>  	select LOONGSON_LIOINTC
>  	select LOONGSON_EIOINTC
>  	select LOONGSON_PCH_PIC

We already have this:

# Supports effective affinity mask
config GENERIC_IRQ_EFFECTIVE_AFF_MASK
       depends on SMP
       bool

Do we really need to express this for every interrupt controller?

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v2] irqchip: LoongArch: Select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP

[Samuel Holland]

On 11/26/22 06:53, Marc Zyngier wrote:
> On Thu, 27 Oct 2022 04:39:09 +0100,
> Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>>
>> An IRQ's effective affinity can only be different from its configured
>> affinity if there are multiple CPUs. Make it clear that this option is
>> only meaningful when SMP is enabled.
>>
>> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
>> ---
>>
>> v2: rebased on 6.1-rc2
>>
>>  drivers/irqchip/Kconfig | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
>> index 7ef9f5e..8461915 100644
>> --- a/drivers/irqchip/Kconfig
>> +++ b/drivers/irqchip/Kconfig
>> @@ -575,7 +575,7 @@ config IRQ_LOONGARCH_CPU
>>  	bool
>>  	select GENERIC_IRQ_CHIP
>>  	select IRQ_DOMAIN
>> -	select GENERIC_IRQ_EFFECTIVE_AFF_MASK
>> +	select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
>>  	select LOONGSON_LIOINTC
>>  	select LOONGSON_EIOINTC
>>  	select LOONGSON_PCH_PIC
> 
> We already have this:
> 
> # Supports effective affinity mask
> config GENERIC_IRQ_EFFECTIVE_AFF_MASK
>        depends on SMP
>        bool
> 
> Do we really need to express this for every interrupt controller?

Unfortunately yes, because "select" does not respect dependencies. So
the "depends on SMP" line does not enforce anything; it only serves to
provide a warning at configure time that the build will break.

Regards,
Samuel

Re: [PATCH v2] irqchip: LoongArch: Select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP

[Marc Zyngier]

On Sat, 26 Nov 2022 23:49:10 +0000,
Samuel Holland <samuel@sholland.org> wrote:
> 
> On 11/26/22 06:53, Marc Zyngier wrote:
> > On Thu, 27 Oct 2022 04:39:09 +0100,
> > Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
> >>
> >> An IRQ's effective affinity can only be different from its configured
> >> affinity if there are multiple CPUs. Make it clear that this option is
> >> only meaningful when SMP is enabled.
> >>
> >> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> >> ---
> >>
> >> v2: rebased on 6.1-rc2
> >>
> >>  drivers/irqchip/Kconfig | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> >> index 7ef9f5e..8461915 100644
> >> --- a/drivers/irqchip/Kconfig
> >> +++ b/drivers/irqchip/Kconfig
> >> @@ -575,7 +575,7 @@ config IRQ_LOONGARCH_CPU
> >>  	bool
> >>  	select GENERIC_IRQ_CHIP
> >>  	select IRQ_DOMAIN
> >> -	select GENERIC_IRQ_EFFECTIVE_AFF_MASK
> >> +	select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
> >>  	select LOONGSON_LIOINTC
> >>  	select LOONGSON_EIOINTC
> >>  	select LOONGSON_PCH_PIC
> > 
> > We already have this:
> > 
> > # Supports effective affinity mask
> > config GENERIC_IRQ_EFFECTIVE_AFF_MASK
> >        depends on SMP
> >        bool
> > 
> > Do we really need to express this for every interrupt controller?
> 
> Unfortunately yes, because "select" does not respect dependencies. So
> the "depends on SMP" line does not enforce anything; it only serves to
> provide a warning at configure time that the build will break.

I understand that. My question was more "how can we avoid doing that
for each and every irqchip".

So far, the only things I can think of are either an intermediate
config symbol that performs the "if SMP" by itself, or spraying checks
for CONFIG_SMP all over the shop. None of which are appealing.

	M.

-- 
Without deviation from the norm, progress is not possible.