Re: [PATCH v1 13/15] platform/x86/amd/pmf: Handle AMT and CQL events for Auto mode

[Shyam Sundar S K <Shyam-sundar.S-k@amd.com>]

Hi Mario,

On 7/29/2022 9:13 PM, Limonciello, Mario wrote:
> On 7/29/2022 06:03, Hans de Goede wrote:
>>>>
>>>> So as for the AMT mode, since that is Lenovo only, I guess that means
>>>> that there is no need to do call amd_pmf_update_slider() when AMT
>>>> is being disabled since at this point the firmware will have
>>>> already set the values.
>>>
>>> Yeah, Shyam made this modification for v2 to make sure that code path
>>> isn't called unless static slider was set in the BIOS.
>>
>> But this code path is only hit when AMT / auto mode is available and
>> when that is true then the static slider should never be set in the BIOS
>> so the whole amd_pmf_update_slider() call on AMT disable can simply
>> be dropped AFAICT.
> 
> The reason to leave it in place but guarded like this is for validation
> of the feature behaves properly from AMD internal systems AMD test BIOS.
>  It can be used to prove out something works properly without needing to
> include extra drivers and software.

Yes. We will need this path to check on the internal CRB system to
validate the 'auto mode'. Whenever the amd-pmf driver gets the AMT
disable event we shall disable the power-settings w.r.t to 'auto mode'.

I moved the handling to amd_pmf_reset_amt() based on Hans review
remarks, and its guarded with a if() check, so that we accidentally
don't land up in updating the static slider.

Also left a note on the same function, so that it provides some
information on why the logic is being done in that way.

> 
>>
>>>
>>>>
>>>> Actually this seems to mean that we must ensure that the AMD-PMF
>>>> code stops touching these settings as soon as the event is received.
>>>>
>>>> Which would imply killing the periodic work when an AMT off event
>>>> is received from within the event handling and then restating it
>>>> when AMT is on (and making sure the work being queued or not state
>>>> matches the AMT on/off state at driver probe time) ?
>>>>
>>>
>>> At first glance this seems plausible, but actually I think it should
>>> stay as is because CQL thermals can be set at any time (that's like a
>>> lap mode sensor event from thinkpad_acpi).  Even when AMT is turned
>>> off, you may want the CQL thermal profile set accordingly.
>>
>> So the CQL code is to handle lapmode when AMT is active. But I would
>> expect the firmware to update the power-limits, etc. for lapmode itself
>> when in performance mode. >
>> The amd_pmf_update_2_cql() function only does things when
>> config_store.current_mode == AUTO_PERFORMANCE (or
>> AUTO_PERFORMANCE_ON_LAP)
>>
>> And that reflects the last mode selected by the auto/AMT mode code, not
>> the mode actual set by thinkpad_acpi so if the last auto selected mode
>> was balanced and then AMT gets disabled because thinkpad_acpi switches
>> to performance mode, then on CQL events after the switch
>> amd_pmf_update_2_cql()
>> will not do anything.
>>
>> To me it seems that when AMT is off the AMD-PMF code should not touch
>> the power-limits, etc. at all and thus it should also always ignore
>> CQL events when AMT is off.
>>
>> This assumes that the firmware takes care of udating the limits for
>> on lap / off lap when thinkpad_acpi's profile is set to performance.
> 
> Where does this assumption come from?  I guess that's how it's done on
> Lenovo's Intel systems?
> 
> AMT and CQL is a new feature on Lenovo AMD systems, this is the way that
> it's supposed to be done here.

Yes, this was newly designed for Lenovo AMD systems. The behavior is
same on windows too (atleast on the RMB laptops today) .

When the system is running in 'auto-mode performance' and the user keeps
the system on his lap, amd-pmf driver receives a 'CQL' event from Lenovo
BIOS. In this case, the amd-pmf driver shall apply thermal limits w.r.t
to 'auto-mode performance-on-lap' and not 'auto-mode performance'.


> 
>>
>> If thinkpad_acpi does not do this then the AMD-PMF code should
>> check what mode has been selected by the thinkpad_acpi code in
>> amd_pmf_update_2_cql() when AMT is off.
>>
> 
> It is up to the firmware (and thinkpad_acpi) to decide when to send
> the CQL events.
> 
> Shyam - any comments here?

Yes, I agree with Mario here.

Thanks,
Shyam