linux-kernel - Re: [PATCH v2 6/6] ARM: tegra: cpuidle: use firmware for power down

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Date:	Wed, 12 Feb 2014 10:56:18 +0900
From:	Alexandre Courbot <acourbot@...dia.com>
To:	Olof Johansson <olof@...om.net>
CC:	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Tomasz Figa <t.figa@...sung.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"gnurou@...il.com" <gnurou@...il.com>
Subject: Re: [PATCH v2 6/6] ARM: tegra: cpuidle: use firmware for power down

On 02/12/2014 10:36 AM, Olof Johansson wrote:
> 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@...dia.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(....);

I might have been overdoing it indeed. Let me submit a v3 just for this 
one patch.

Thanks!
Alex.

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