From: mpeg.blue@free•fr (Mason)
To: linux-arm-kernel@lists•infradead.org
Subject: RFC on cpufreq implementation
Date: Fri, 16 Jan 2015 15:00:14 +0100 [thread overview]
Message-ID: <54B9196E.1030302@free.fr> (raw)
In-Reply-To: <54B8F19F.8060108@free.fr>
On 16/01/2015 12:10, Mason wrote:
> I didn't find where WFI is called :-(
>
> In kernel/cpu/idle.c (file seems to have been removed in 3.15)
> cpu_idle_loop() calls arch_cpu_idle()
> http://lxr.free-electrons.com/source/kernel/cpu/idle.c?v=3.14#L98
>
> In arch/kernel/process.c
> http://lxr.free-electrons.com/source/arch/arm/kernel/process.c?v=3.14#L173
> /*
> * Called from the core idle loop.
> */
> void arch_cpu_idle(void)
> {
> if (cpuidle_idle_call())
> default_idle();
> }
>
> default_idle calls cpu_do_idle (by default), a macro for cpu_v7_do_idle
> which executes dsb+wfi, BUT...
>
> ifndef CONFIG_CPU_IDLE then
> static inline int cpuidle_idle_call(void) { return -ENODEV; }
>
> Does that mean I MUST define CONFIG_CPU_IDLE if I want the idle
> loop to call wfi (to save power), even if I don't have a cpuidle
> driver?
For the record, I read the code wrong.
cpuidle_idle_call() always returns -ENODEV, so the test
"if (cpuidle_idle_call())" is always true, and we always
call default_idle() and everything works as expected.
Sorry for the noise.
next prev parent reply other threads:[~2015-01-16 14:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-15 17:24 RFC on cpufreq implementation Mason
2015-01-16 9:08 ` Krzysztof Kozlowski
2015-01-16 11:10 ` Mason
2015-01-16 11:43 ` Krzysztof Kozlowski
2015-01-16 12:10 ` Javi Merino
2015-01-16 14:00 ` Mason [this message]
2015-01-19 7:52 ` Viresh Kumar
2015-01-19 22:03 ` Mason
2015-01-20 3:55 ` Viresh Kumar
2015-01-19 9:22 ` Amit Kucheria
2015-01-19 22:13 ` Mason
2015-01-29 16:43 ` Mason
2015-01-30 1:15 ` Viresh Kumar
2015-01-30 23:44 ` Mason
2015-02-02 3:58 ` Viresh Kumar
2015-02-04 0:07 ` Mason
2015-02-04 0:32 ` Måns Rullgård
2015-02-04 4:12 ` Viresh Kumar
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