Re: [PATCH] ACPI / Processor: add sysfs support for low power idle

["Prakash, Prashanth" <pprakash@codeaurora.org>]

Hi Rafael,

On 6/27/2017 5:59 PM, Rafael J. Wysocki wrote:
> On Fri, May 19, 2017 at 9:19 PM, Prashanth Prakash
> <pprakash@codeaurora.org> wrote:
>> Add support to expose idle statistics maintained by platform to
>> userspace via sysfs in addition to other data of interest from
>> each LPI(Low Power Idle) state.
>>
>> LPI described in section 8.4.4 of ACPI spec 6.1 provides different
>> methods to obtain idle statistics maintained by the platform. These
>> show a granular view of how each of the LPI state is being used at
>> different level of hierarchy. sysfs data is exposed at each level in
>> the hierarchy by creating a directory named 'lpi' at each level and
>> the LPI state information is presented under it. Below is the
>> representation of LPI information at one such level in the hierarchy
>>
>> .../ACPI00XX: XX/lpi
>>         |-> state0
>>         |       |-> desc
>>         |       |-> time
>>         |       |-> usage
>>         |       |-> latency
>>         |       |-> min_residency
>>         |
>>         <<more states>>
>>
>> ACPI00XX can be ACPI0007(processor) or ACPI0010(processor container)
>>
>> stateX contains information related to a specific LPI state defined
>> in the LPI ACPI tables.
> That needs to be documented under Documentation/ABI/.
Sure, I will create a patch updating the ABI documentation.
>> diff --git a/include/acpi/processor.h b/include/acpi/processor.h
>> index c1ba00f..b99b84b 100644
>> --- a/include/acpi/processor.h
>> +++ b/include/acpi/processor.h
>> @@ -79,6 +79,19 @@ struct acpi_lpi_state {
>>         u8 index;
>>         u8 entry_method;
>>         char desc[ACPI_CX_DESC_LEN];
>> +       struct acpi_generic_address res_cntr;
>> +       struct acpi_generic_address usage_cntr;
> Is there any reason why these two cannot be of type struct acpi_power_register?
acpi_read() API required reference to acpi_generic_address (our only use case is to read the
register), so keeping this data in acpi_generic_address makes the code little simpler.

--
Thanks,
Prashanth