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authorJoseph Lo <josephl@nvidia.com>2013-01-16 17:33:55 +0000
committerStephen Warren <swarren@nvidia.com>2013-01-28 11:20:38 -0700
commit1d328606c66b9bb1c0552f585943d596f37ae3b9 (patch)
treeebb8a6e60de7b5b96100ffbcda57445116a906ef /drivers/clk
parentafec581c4b53e03a97d9ef1b7a746a67967573cf (diff)
downloadvexpress-lsk-1d328606c66b9bb1c0552f585943d596f37ae3b9.tar.gz
ARM: tegra20: cpuidle: apply coupled cpuidle for powered-down mode
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". Based on the work by: Colin Cross <ccross@android.com> Gary King <gking@nvidia.com> Signed-off-by: Joseph Lo <josephl@nvidia.com> Acked-by: Colin Cross <ccross@android.com> Signed-off-by: Stephen Warren <swarren@nvidia.com>
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