Re: [PATCH] arch: arm64: add early_param idle=<wfi|yield|nop>

[Joshua Peisach]

On Sun Jul 5, 2026 at 6:02 AM EDT, Yureka Lilian wrote:
> +
> +enum idle_mode idle = WFI;
> +
> +/* User can over-ride above with "idle=<wfi|yield|nop>" in cmdline */
> +static int __init setup_idle(char *s)
> +{
> +	if (!s)
> +		return -1;
> +	else if (!strcmp(s, "wfi"))
> +		idle = WFI;
> +	else if (!strcmp(s, "yield"))
> +		idle = YIELD;
> +	else if (!strcmp(s, "nop"))
> +		idle = NOP;
> +	else
> +		return -1;
> +
> +	return 0;
> +}
> +early_param("idle", setup_idle);
> +
>  /*
>   *	cpu_do_idle()
>   *
> @@ -26,8 +48,13 @@ void __cpuidle cpu_do_idle(void)
>  
>  	arm_cpuidle_save_irq_context(&context);
>  
> -	dsb(sy);
> -	wfi();
> +	if (likely(idle == WFI)) {
> +		dsb(sy);
> +		wfi();
> +	} else if (idle == YIELD) {
> +		dsb(sy);
> +		asm volatile("yield" ::: "memory");
> +	}

And otherwise...........?

I guess it would be NOP, so do nothing - is this expected behavior?

-Josh