Re: [External] Re: [RFC] ACPI: platform-profile: support for AC vs DC modes

[Mark Pearson <markpearson@lenovo.com>]

On 2022-03-14 11:31, Hans de Goede wrote:
> Hi,
> 
> On 3/14/22 15:43, Hans de Goede wrote:
>> Hi Mario,
>>
>> On 3/14/22 14:39, Limonciello, Mario wrote:
>>> [Public]
>>>
>>>>>
>>>>> I cycled through a few different implementations but came down on what I
>>>>> proposed. I considered 6 values - but I don't think that makes sense and
>>>>> makes it overall more complicated than it needs to be and less flexible.
>>>>
>>>> Ah, so to be clear, my 2 scenarios above were theoretical scenarios,
>>>> because I'm wondering how the firmware API here actually looks like,
>>>> something which so far is not really clear to me.
>>>>
>>>> When you say that you considered using 6 values, then I guess that
>>>> the firmware API actually offers 6 values which we can write to a single slot:
>>>> ac-low-power,dc-lowpower,ac-balanced,dc-balanced,ac-performance,dc-
>>>> performance
>>>>
>>>> ?
>>>>
>>>> But that is not what the RFC patch that started this thread shows at all,
>>>> the API to the driver is totally unchanged and does not get passed
>>>> any info on ac/dc selection ?  So it seems to me that the ACPI API Linux
>>>> uses for this writes only 1 of 3 values to a single slot and the EC automatically
>>>> switches between say ac-balanced and dc-balanced internally.
>>>>
>>>> IOW there really being 2 differently tuned balance-profiles is not visible to
>>>> the OS at all, this is handled internally inside the EC, correct ?
>>>>
>>>
>>> No - on Lenovo's platform there are 6 different profiles that can be selected
>>> from the kernel driver.  3 are intended for use on battery, 3 are intended for
>>> use on AC.
>>
>> Ah, I already got that feeling from the rest of the thread, so I reread
>> Mark's RFC again before posting my reply today and the RFC looked like
>> the same 3 profiles were being set and the only functionality added
>> was auto profile switching when changing between AC/battery.
>>
>> Thank you for clarifying this. Having 6 different stories
>> indeed is a very different story.
>>
>>>> Otherwise I would expect the kernel internal driver API to also change and
>>>> to also see a matching thinkpad_acpi patch in the RFC series?
>>>
>>> The idea I see from Mark's thread was to send out RFC change for the platform profile
>>> and based on the direction try to implement the thinkpad-acpi change after that.
>>>
>>> Because of the confusion @Mark I think you should send out an RFC v2 with thinkpad acpi
>>> modeled on top of this the way that you want.
>>
>> I fully agree and since you introduce the concept of being on AC/battery to the
>> drivers/acpi/platform_profile.c cpde, please change the 
>> profile_set and profile_get function prototypes in struct platform_profile_handler
>> to also take a "bool on_battery" extra argument and use that in the thinkpad
>> driver to select either the ac or the battery tuned low/balanced/performance 
>> profile.
>>
>> And please also include an update to Documentation/ABI/testing/sysfs-platform_profile
>> in the next RFC.
>>
>> Also notice how I've tried to consistently use AC/battery in my last reply,
>> DC really is not a good term for "on battery". AC also is sort of dubious
>> for "connected to an external power-supply" but its use for that is sorta
>> common and it is nice and short.
> 
> One last request for the v2 RFC, please also Cc Bastien Nocera, so that
> he can take a look at the proposed uapi changes from the userspace side
> of things.
> 
Ack - will do.
Thanks!
Mark