[PATCH 7/7] ARM: tegra30: cpuidle: add LP2 driver for CPU0

[Colin Cross]

On Mon, Oct 15, 2012 at 8:59 AM, Stephen Warren <swarren at wwwdotorg.org> wrote:
> On 10/15/2012 01:56 AM, Joseph Lo wrote:
>> There is still one thing you should know. Because we are planning to
>> upstream "CPUquiet" framework that is a CPU auto hotplug mechanism. It
>> will auto hotplug the CPUs depends on the system is busy or not. So when
>> system is idle, there will be only one CPU online (i.e, CPU0). The
>> secondary CPUs will all be hot plugged (i.e, offline and power gate). We
>> need to think about do we still need coupled cpuidle on Tegra30 if we
>> are going to use "CPUquiet".
>
> CPUquiet isn't relevant at all. First, a user may presumably disable
> CPUquiet's Kconfig option (it had better have one, and the system had
> better work with it disabled). Second, even if CPUquiet is enabled, I
> don't imagine there is a 100% guarantee that hot(un)plug will happen
> before cpuidle kicks in, is there? Finally, is there any guarantee that
> CPUquiet will actually be accepted upstream?

CPUquiet is a glorified hotplug governor, and hotplug governors have
been widely rejected upstream, so I wouldn't plan on seeing it
accepted.