linux-kernel - Re: [PATCH] ARM: ux500: fix prcmu_is_cpu_in

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Date:   Wed, 16 Nov 2016 16:35:12 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: ux500: fix prcmu_is_cpu_in_wfi() calculation

On Wed, Nov 16, 2016 at 04:20:37PM +0100, Arnd Bergmann wrote:
> This function clearly never worked and always returns true,
> as pointed out by gcc-7:
> 
> arch/arm/mach-ux500/pm.c: In function 'prcmu_is_cpu_in_wfi':
> arch/arm/mach-ux500/pm.c:137:212: error: ?: using integer constants in boolean context, the expression will always evaluate to 'true' [-Werror=int-in-bool-context]
> 
> With the added braces, the condition actually makes sense.
> 
> Fixes: 34fe6f107eab ("mfd : Check if the other db8500 core is in WFI")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  arch/arm/mach-ux500/pm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/mach-ux500/pm.c b/arch/arm/mach-ux500/pm.c
> index 8538910db202..a970e7fcba9e 100644
> --- a/arch/arm/mach-ux500/pm.c
> +++ b/arch/arm/mach-ux500/pm.c
> @@ -134,8 +134,8 @@ bool prcmu_pending_irq(void)
>   */
>  bool prcmu_is_cpu_in_wfi(int cpu)
>  {
> -	return readl(PRCM_ARM_WFI_STANDBY) & cpu ? PRCM_ARM_WFI_STANDBY_WFI1 :
> -		     PRCM_ARM_WFI_STANDBY_WFI0;
> +	return readl(PRCM_ARM_WFI_STANDBY) &
> +		(cpu ? PRCM_ARM_WFI_STANDBY_WFI1 : PRCM_ARM_WFI_STANDBY_WFI0);
>  }
>  
>  /*

Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>

Very strange this board did not hang with this broken function.

It is used in a critical function for cpuidle. Is it possible to make a quick
test with this cpuidle test program [1] ?

Thanks!

  -- Daniel

[1] https://git.linaro.org/power/pm-qa.git/tree/cpuidle/cpuidle_killer.c

-- 

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