Re: [PATCH] PM / suspend: Always use deepest C-state in the "freeze" sleep state

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 05/12/2014 04:19 PM, Li, Aubrey wrote:
> On 2014/5/12 22:08, Daniel Lezcano wrote:
>> On 05/05/2014 12:51 AM, Rafael J. Wysocki wrote:
>>> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>>>
>>> If freeze_enter() is called, we want to bypass the current cpuidle
>>> governor and always use the deepest available (that is, not disabled)
>>> C-state, because we want to save as much energy as reasonably possible
>>> then and runtime latency constraints don't matter at that point, since
>>> the system is in a sleep state anyway.
>>>
>>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>>> ---
>>>
>>> This is on top of https://patchwork.kernel.org/patch/4071541/ .
>>>
>>
>> Wouldn't make sense to revisit play_dead instead ?
>>
> play_dead() is broken.
>
> Even if it works, we still should rely on cpuidle driver to place the
> CPUs into the deepest c-state, because there is no architectural way to
> enter deepest c-state and what play_dead() does is a bad assumption.

Ok, let me rephrase it. Why not revisiting cpuidle_play_dead instead ?


-- 
  <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog