Re: [PATCH] cpuidle: reinitialize power_usage values when adding/removingC-states

From: Daniel Lezcano
Date: Wed Oct 17 2012 - 06:44:20 EST

On 10/17/2012 12:31 PM, Daniel Lezcano wrote:
> On 10/17/2012 12:39 AM, Julius Werner wrote:
>> When cpuidle drivers do not supply explicit power_usage values,
>> cpuidle/driver.c inserts dummy values instead. When a running processor
>> dynamically gains new C-states (e.g. after ACPI events), the power_usage
>> values of those states will stay uninitialized, and cpuidle governors
>> will never choose to enter them.
>> This patch moves the dummy value initialization from
>> cpuidle_register_driver to cpuidle_enable_device, which drivers such as
>> acpi/processor_idle.c will call again when they add or remove C-states.
>> Tested and verified on an Acer AC700 Chromebook, which supports the C3
>> state only when it switches from AC to battery power.
>> Signed-off-by: Julius Werner <jwerner@xxxxxxxxxxxx>
>> ---
> This is specific to the acpi and should be handled in the
> processor_idle.c file instead of the cpuidle core code.
> Could be the function 'acpi_processor_cst_has_changed' the right place
> to set a dummy power value for the power in the new C-state ?

btw, good catch ! :)

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