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

[Mark Pearson <markpearson@lenovo.com>]

On 2022-03-14 12:56, Hans de Goede wrote:
> Hi,
> 
> On 3/14/22 16:32, Mark Pearson wrote:
>>
>>
>> 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.
> 
> So I've been thinking a bit more about this while I was outside for some
> fresh air.
> 
> First of all let me say that I do agree that the having in essence 6
> different profiles thing needs a kernel solution.
> 
> What I'm not entirely sure about is if this needs to be something
> generic, with a new userspace-API as you proposed in the v1 RFC,
> or if it would be better to just solve this in thinkpad_acpi.c .
> 
> Now that I've a better grasp of the problem, I'll start a new email
> thread on this tomorrow with all the various take-holders in the Cc
> to try and answer that question.
> 
> It probably is a good idea to wait with doing a v2 of the RFC until
> we've had that discussion...
> 
No problem - and thanks! I'll hold off until we have a better idea where
we are going.
If having some example code is useful though just let me know

Mark