linux-kernel - Re: [PATCH v5 3/3] irqchip/loongson-eiointc: Refine irq affinity setting during resume

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Date: Thu, 14 Mar 2024 22:34:15 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Bibo Mao <maobibo@...ngson.cn>, Jiaxun Yang <jiaxun.yang@...goat.com>, 
	linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Sergey Shtylyov <s.shtylyov@....ru>, lvjianmin@...ngson.cn
Subject: Re: [PATCH v5 3/3] irqchip/loongson-eiointc: Refine irq affinity
 setting during resume

On Wed, Mar 13, 2024 at 8:39 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> On Wed, Mar 13 2024 at 14:20, Huacai Chen wrote:
> > On Tue, Feb 13, 2024 at 5:49 PM Thomas Gleixner <tglx@...utronix.de> wrote:
> >>
> >> On Tue, Jan 30 2024 at 16:27, Bibo Mao wrote:
> >> > During suspend and resume, CPUs except CPU0 can be hot-unpluged and IRQs
> >> > will be migrated to CPU0. So it is not necessary to restore irq affinity
> >> > for eiointc irq controller when system resumes.
> >>
> >> That's not the reason. The point is that eiointc_router_init() which is
> >> invoked in the resume path affines all interrupts to CPU0, so the
> >> restore operation is redundant, no?
> > I'm sorry for the late response but I think this is a little wrong.
> > When irq_migrate_all_off_this_cpu() is called at hot-unplug, if an
> > irqdesc is irqd_affinity_is_managed() then its affinity is untouched
> > (doesn't change to CPU0). Then after resume we should not keep its
> > affinity on CPU0 set by eiointc_router_init() , but need to restore
> > its old affinity.
>
> Affinity is restored when the interrupt is started up again, so yes the
> affinity setting should not be changed.
OK, thanks.

Huacai