From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH V3 5/5] ARM: tegra20: cpuidle: apply coupled cpuidle for powered-down mode
Date: Thu, 20 Dec 2012 10:54:09 -0700 [thread overview]
Message-ID: <50D350C1.6070400@wwwdotorg.org> (raw)
In-Reply-To: <1355797861-12759-6-git-send-email-josephl@nvidia.com>
On 12/17/2012 07:31 PM, Joseph Lo wrote:
> The "powered-down" cpuidle mode of Tegra20 needs the CPU0 be the last one
> core to go into this mode before other core. The coupled cpuidle framework
> can help to sync the MPCore to coupled state then go into "powered-down"
> idle mode together. The driver can just assume the MPCore come into
> "powered-down" mode at the same time. No need to take care if the CPU_0
> goes into this mode along and only can put it into safe idle mode (WFI).
>
> The powered-down state of Tegra20 requires power gating both CPU cores.
> When the secondary CPU requests to enter powered-down state, it saves
> its own contexts and then enters WFI for waiting CPU0 in the same state.
> When the CPU0 requests powered-down state, it attempts to put the secondary
> CPU into reset to prevent it from waking up. Then power down both CPUs
> together and power off the cpu rail.
>
> Be aware of that, you may see the legacy power state "LP2" in the code
> which is exactly the same meaning of "CPU power down".
> diff --git a/arch/arm/mach-tegra/cpuidle-tegra20.c b/arch/arm/mach-tegra/cpuidle-tegra20.c
> +static void tegra20_wake_reset_cpu_1(void)
Nit/bikeshe: I think tegra20_wake_from_reset_cpu_1() might be a slightly
more descriptive name? I assume the function works on CPU1, which is
assumed to be in reset, and removes reset from the CPU so it boots.
> @@ -137,6 +241,9 @@ int __init tegra20_cpuidle_init(void)
> for_each_possible_cpu(cpu) {
> dev = &per_cpu(tegra_idle_device, cpu);
> dev->cpu = cpu;
> +#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
> + dev->coupled_cpus = *cpu_online_mask;
> +#endif
That CONFIG option is selected by ARCH_TEGRA_2x_SOC, which must be
enabled for this file to be compiled. So, you can drop the ifdef, and
make the code uncondtional.
next prev parent reply other threads:[~2012-12-20 17:54 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-18 2:30 [PATCH V3 0/5] ARM: tegra20: cpuidle: add power-down state Joseph Lo
2012-12-18 2:30 ` [PATCH V3 1/5] ARM: tegra: add pending SGI checking API Joseph Lo
2012-12-18 2:42 ` Colin Cross
2012-12-18 2:57 ` Joseph Lo
2012-12-18 10:15 ` Peter De Schrijver
2012-12-18 19:36 ` Colin Cross
2012-12-19 1:06 ` Joseph Lo
2012-12-19 3:47 ` Joseph Lo
2012-12-20 7:16 ` Santosh Shilimkar
2012-12-20 9:34 ` Peter De Schrijver
2012-12-20 9:49 ` Santosh Shilimkar
2012-12-20 9:59 ` Peter De Schrijver
2012-12-20 10:24 ` Santosh Shilimkar
2012-12-20 11:14 ` Peter De Schrijver
2012-12-20 12:06 ` Santosh Shilimkar
2012-12-18 2:30 ` [PATCH V3 2/5] ARM: tegra20: cpuidle: add powered-down state for secondary CPU Joseph Lo
2012-12-18 2:46 ` Colin Cross
2012-12-18 3:06 ` Joseph Lo
2012-12-20 17:43 ` Stephen Warren
2012-12-21 6:36 ` Joseph Lo
2012-12-21 21:04 ` Stephen Warren
2012-12-18 2:30 ` [PATCH V3 3/5] ARM: tegra20: clocks: add CPU low-power function into tegra_cpu_car_ops Joseph Lo
2012-12-20 17:46 ` Stephen Warren
2012-12-21 5:02 ` Joseph Lo
2012-12-21 21:10 ` Stephen Warren
2012-12-18 2:31 ` [PATCH V3 4/5] ARM: tegra20: flowctrl: add support for cpu_suspend_enter/exit Joseph Lo
2012-12-18 2:31 ` [PATCH V3 5/5] ARM: tegra20: cpuidle: apply coupled cpuidle for powered-down mode Joseph Lo
2012-12-18 10:18 ` Peter De Schrijver
2012-12-20 17:54 ` Stephen Warren [this message]
2012-12-21 7:10 ` Joseph Lo
2012-12-21 21:06 ` Stephen Warren
2013-01-02 19:05 ` [PATCH V3 0/5] ARM: tegra20: cpuidle: add power-down state Stephen Warren
2013-01-03 8:39 ` Joseph Lo
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