linux-kernel - Re: [PATCH 5/5] ARM: tegra: cpuidle: use firmware call for power down

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Date:	Wed, 22 Jan 2014 13:45:00 -0700
From:	Stephen Warren <swarren@...dotorg.org>
To:	Alexandre Courbot <acourbot@...dia.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Russell King <linux@....linux.org.uk>
CC:	Olof Johansson <olof@...om.net>,
	linux-arm-kernel@...ts.infradead.org, linux-tegra@...r.kernel.org,
	linux-kernel@...r.kernel.org, gnurou@...il.com
Subject: Re: [PATCH 5/5] ARM: tegra: cpuidle: use firmware call for power
 down

On 01/21/2014 03:10 AM, Alexandre Courbot wrote:
> Invoke the do_idle() firmware call before suspending a CPU so that the
> underlying firmware (if any) can take necessary action.

> diff --git a/arch/arm/mach-tegra/cpuidle-tegra114.c b/arch/arm/mach-tegra/cpuidle-tegra114.c

> @@ -45,6 +46,8 @@ static int tegra114_idle_power_down(struct cpuidle_device *dev,
>  
>  	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
>  
> +	call_firmware_op(do_idle);
> +
>  	cpu_suspend(0, tegra30_sleep_cpu_secondary_finish);
>  
>  	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);

Don't you need to have the kernel also *not* do something when entering
idle; doesn't the FW op replace some of the register writes that the
kernel would otherwise be doing?
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