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

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 7/29/22 19:40, Shyam Sundar S K wrote:
> 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'.

The question here is not about the 'auto-mode performance' mode
but what to do when AMT / 'auto-mode performance' is disabled.

What should the behavior of the AMD-PMf code be when it receives
a CQL event when AMT is disabled ?

>>> 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.

Regards,

Hans