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

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Message-ID: <7e2275d5-19dc-555e-e8e1-ed79b408c0e3@amd.com>
Date: Wed, 31 Jul 2024 12:21:05 +0800
From: Xiaojian Du <xiaojidu@....com>
To: David Wang <00107082@....com>
Cc: perry.yuan@....com, Alexander.Deucher@....com, Li.Meng@....com,
 Mario.Limonciello@....com, Xiaojian.Du@....com, Xinmei.Huang@....com,
 gautham.shenoy@....com, linux-kernel@...r.kernel.org,
 linux-pm@...r.kernel.org, rafael.j.wysocki@...el.com, viresh.kumar@...aro.org
Subject: Re: [Regression] 6.11.0-rc1: AMD CPU boot with error when CPPC
 feature disabled by BIOS


On 2024/7/31 11:39, David Wang wrote:
> At 2024-07-31 11:16:14, "Xiaojian Du" <xiaojidu@....com> wrote:
>> On 2024/7/31 8:25, David Wang wrote:
>>> Hi Du,
>>>
>>> Thanks for the quick response
>>>
>>> ...
>>> 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?
Warning is not enough, error will guide user to switch to acpi cpu 
driver or seek more support from OEM.
>>> Is it possible, that those two condition coexists: CPPC is disabled by BIOS, and  amd-pstate could function properly?
>>>
>>>   

No possible, the current amd-pstate driver is based on CPPC feature.

Thanks.
Xiaojian

>>> Thanks
>>> David
>>>