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Message-ID: <cf953917-efe4-8254-f468-3baf7e596483@sholland.org>
Date:   Sat, 26 Nov 2022 17:49:10 -0600
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To:     Marc Zyngier <maz@kernel.org>, Tiezhu Yang <yangtiezhu@loongson.cn>
Cc:     Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org
References: <1666841949-5244-1-git-send-email-yangtiezhu@loongson.cn>
 <87v8n1ubbj.wl-maz@kernel.org>
From:   Samuel Holland <samuel@sholland.org>
Subject: Re: [PATCH v2] irqchip: LoongArch: Select
 GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
In-Reply-To: <87v8n1ubbj.wl-maz@kernel.org>
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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