Date: Tue, 11 Feb 2014 17:36:50 -0800
From: Olof Johansson <olof@lixom.net>
To: Alexandre Courbot <acourbot@nvidia.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Russell King <linux@arm.linux.org.uk>,
        Tomasz Figa <t.figa@samsung.com>, linux-arm-kernel@lists.infradead.org,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
        gnurou@gmail.com
Subject: Re: [PATCH v2 6/6] ARM: tegra: cpuidle: use firmware for power down
Message-ID: <20140212013650.GA7584@quad.lixom.net>
References: <1391747706-1847-1-git-send-email-acourbot@nvidia.com>
 <1391747706-1847-7-git-send-email-acourbot@nvidia.com>
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On Fri, Feb 07, 2014 at 01:35:06PM +0900, Alexandre Courbot wrote:
> Attempt to invoke the prepare_idle() and do_idle() firmware calls
> to power down a CPU so an underlying firmware gets informed of
> the idle operation and performs it by itself if designed in such a way.
> 
> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
> ---
>  arch/arm/mach-tegra/cpuidle-tegra114.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-tegra/cpuidle-tegra114.c b/arch/arm/mach-tegra/cpuidle-tegra114.c
> index e0b87300243d..558067ddc186 100644
> --- a/arch/arm/mach-tegra/cpuidle-tegra114.c
> +++ b/arch/arm/mach-tegra/cpuidle-tegra114.c
> @@ -19,6 +19,7 @@
>  #include <linux/cpuidle.h>
>  #include <linux/cpu_pm.h>
>  #include <linux/clockchips.h>
> +#include <asm/firmware.h>
>  
>  #include <asm/cpuidle.h>
>  #include <asm/suspend.h>
> @@ -45,7 +46,15 @@ static int tegra114_idle_power_down(struct cpuidle_device *dev,
>  
>  	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
>  
> -	cpu_suspend(0, tegra30_sleep_cpu_secondary_finish);
> +	call_firmware_op(prepare_idle);
> +
> +	switch (call_firmware_op(do_idle)) {
> +	case -ENOSYS:
> +		cpu_suspend(0, tegra30_sleep_cpu_secondary_finish);
> +		break;
> +	default:
> +		break;

Do you expect other cases down the road? If not, this is a simple if instead:

	/* Only call cpu_suspend if TF didn't handle the pre-suspend logic */
	if (call_firmware_op(do_idle) == -ENOSYS)
		cpu_suspend(....);


-Olof
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