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Date: Wed, 22 Jul 2026 22:43:09 +0100
From: Will Deacon <will@kernel.org>
To: Yureka Lilian <yureka@cyberchaos.dev>
Cc: Jonathan Corbet <corbet@lwn.net>,
	Shuah Khan <skhan@linuxfoundation.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] arch: arm64: add early_param idle=<wfi|yield|nop>
Message-ID: <amE5bX0jey6WS0U1@willie-the-truck>
References: <20260711-arm64-idle-param-v2-1-0ab67652a435@cyberchaos.dev>
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In-Reply-To: <20260711-arm64-idle-param-v2-1-0ab67652a435@cyberchaos.dev>

On Sat, Jul 11, 2026 at 09:35:25AM +0200, Yureka Lilian wrote:
> diff --git a/arch/arm64/lib/delay.c b/arch/arm64/lib/delay.c
> index e278e060e78a..2452990ed37a 100644
> --- a/arch/arm64/lib/delay.c
> +++ b/arch/arm64/lib/delay.c
> @@ -15,6 +15,8 @@
>  
>  #include <clocksource/arm_arch_timer.h>
>  
> +#include "../kernel/idle.h"
> +
>  #define USECS_TO_CYCLES(time_usecs)			\
>  	xloops_to_cycles((time_usecs) * 0x10C7UL)
>  
> @@ -49,7 +51,8 @@ void __delay(unsigned long cycles)
>  		 * Start with WFIT. If an interrupt makes us resume
>  		 * early, use a WFET loop to complete the delay.
>  		 */
> -		wfit(end);
> +		if (likely(idle == ARM64_IDLE_WFI))
> +			wfit(end);

Rather than scatter the idle implementation check across all users of
WFI*, why not move this into the macro itself? That way, the callers can
all stay like they are but the macro behaves as specified.

Will