Re:Re: [Regression] 6.11.0-rc1: AMD CPU boot with error when CPPC feature disabled by BIOS

[David Wang]

At 2024-07-31 11:16:14, "Xiaojian Du" <xiaojidu@xxxxxxx> wrote:
>
>On 2024/7/31 8:25, David Wang wrote:
>> Hi Du,
>>
>> Thanks for the quick response
>>
...
>>>
>>> Target system, including CPU+baseboard+BIOS, is supposed to enable and
>>> use CPPC feature for better Performance per Watt.
>> I agree that the warning guide makes total sense,  but  the  *errors* does not, why bother trying and report error when the feature is disabled by BIOS.
>>
>It has to do that.
>AMD strongly recommends users to enable this feature, but each OEM will 
>have customized BIOS, some support CPPC but disable by default,
>some support CPPC and enable by default, and some disable CPPC directly 
>without providing switch option.
>
>Since newer Linux kernel enables the amd-pstate driver by default, and 
>newer AMD Zen X CPU supports this feature,
>but user find that CPPC is not effective under their software and 
>hardware combination,
>if this driver does not try to load module and print no information, it 
>will mislead users that the problem is caused by the amd-pstate driver.
>
>Thanks,
>Xiaojian
>

I feel that you are arguing for the warning and the errors separately.
Separately,   I agree warning or error message make sense as you explained,  but together I feel confused:
Receiving a warning that CPPC feature is disable by BIOS already notify users that amd-pstate would not work, right?
Is it possible, that those two condition coexists: CPPC is disabled by BIOS, and  amd-pstate could function properly?


Thanks
David