Re: [PATCH] irqchip/sifive-plic: Respect mask state when setting affinity

From: Nam Cao <namcao@linutronix.de>
To: Inochi Amaoto <inochiama@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Samuel Holland <samuel.holland@sifive.com>
Cc: Inochi Amaoto <inochiama@gmail.com>,
	linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
	Yixun Lan <dlan@gentoo.org>, Longbin Li <looong.bin@gmail.com>
Subject: Re: [PATCH] irqchip/sifive-plic: Respect mask state when setting affinity
Date: Thu, 07 Aug 2025 14:39:42 +0200	[thread overview]
Message-ID: <87fre3mhkh.fsf@yellow.woof> (raw)
In-Reply-To: <20250807111806.741706-1-inochiama@gmail.com>

Inochi Amaoto <inochiama@gmail.com> writes:

> The plic_set_affinity always call plic_irq_enable(), which clears up
> the priority setting even the irq is only masked. This make the irq
> unmasked unexpectly.
>
> Replace the plic_irq_enable/disable() with plic_irq_toggle() to
> avoid changing priority setting.
>
> Suggested-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
> ---
>  drivers/irqchip/irq-sifive-plic.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index bf69a4802b71..5bf5050996da 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -148,6 +148,7 @@ static void plic_irq_enable(struct irq_data *d)
>  
>  static void plic_irq_disable(struct irq_data *d)
>  {
> +	plic_irq_mask(d);
>  	plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 0);
>  }

This part is not required for the problem you are addressing, right?

I do not oppose the change, I'm just curious if I miss something here.

>  
> @@ -179,12 +180,14 @@ static int plic_set_affinity(struct irq_data *d,
>  	if (cpu >= nr_cpu_ids)
>  		return -EINVAL;
>  
> -	plic_irq_disable(d);
> +	/* Invalidate the original routing entry */
> +	plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 0);
>  
>  	irq_data_update_effective_affinity(d, cpumask_of(cpu));
>  
> +	/* Setting the new routing entry if irq is enabled */
>  	if (!irqd_irq_disabled(d))
> -		plic_irq_enable(d);
> +		plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 1);
>  
>  	return IRQ_SET_MASK_OK_DONE;
>  }

This part makes sense:

Reviewed-by: Nam Cao <namcao@linutronix.de>
Tested-by: Nam Cao <namcao@linutronix.de> # VisionFive 2

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