linux-kernel - Re: [PATCH 1/6] ACPI: CPPC: enable AMD CPPC V2 support for family 17h processors

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Date: Wed, 31 Jan 2024 15:45:36 -0600
From: Mario Limonciello <mario.limonciello@....com>
To: Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.com,
 viresh.kumar@...aro.org, Ray.Huang@....com, gautham.shenoy@....com,
 Borislav.Petkov@....com
Cc: Alexander.Deucher@....com, Xinmei.Huang@....com, Xiaojian.Du@....com,
 Li.Meng@....com, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] ACPI: CPPC: enable AMD CPPC V2 support for family 17h
 processors

On 1/31/2024 02:50, Perry Yuan wrote:
> As there are some AMD processors which only support CPPC V2 firmware and
> BIOS implementation, the amd_pstate driver will be failed to load when
> system booting with below kernel warning message:
> 
> [    0.477523] amd_pstate: the _CPC object is not present in SBIOS or ACPI disabled
> 
> To make the amd_pstate driver can be loaded on those TR40 processors, it
> needs to match x86_model from 0x30 to 0x7F for family 17H.
> With the change, the system can load amd_pstate driver as expected.
> 
> Reported-by: Gino Badouri <badouri.g@...il.com>
> Issue: https://bugzilla.kernel.org/show_bug.cgi?id=218171
s/Issue/Closes/
> Fixes: fbd74d1689 ("ACPI: CPPC: Fix enabling CPPC on AMD systems with shared memory")
> Signed-off-by: Perry Yuan <perry.yuan@....com>

One minor change above.

Reviewed-by: Mario Limonciello <mario.limonciello@....com>

> ---
>   arch/x86/kernel/acpi/cppc.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c
> index 8d8752b44f11..ff8f25faca3d 100644
> --- a/arch/x86/kernel/acpi/cppc.c
> +++ b/arch/x86/kernel/acpi/cppc.c
> @@ -20,7 +20,7 @@ bool cpc_supported_by_cpu(void)
>   		    (boot_cpu_data.x86_model >= 0x20 && boot_cpu_data.x86_model <= 0x2f)))
>   			return true;
>   		else if (boot_cpu_data.x86 == 0x17 &&
> -			 boot_cpu_data.x86_model >= 0x70 && boot_cpu_data.x86_model <= 0x7f)
> +			 boot_cpu_data.x86_model >= 0x30 && boot_cpu_data.x86_model <= 0x7f)
>   			return true;
>   		return boot_cpu_has(X86_FEATURE_CPPC);
>   	}