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Date: Fri, 2 Feb 2024 09:17:10 -0600
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Subject: Re: [PATCH v2 5/6] cppc_acpi: print error message if CPPC is
 unsupported
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To: Perry Yuan <perry.yuan@amd.com>, rafael.j.wysocki@intel.com,
 viresh.kumar@linaro.org, Ray.Huang@amd.com, gautham.shenoy@amd.com,
 Borislav.Petkov@amd.com
Cc: Alexander.Deucher@amd.com, Xinmei.Huang@amd.com, Xiaojian.Du@amd.com,
 Li.Meng@amd.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
References: <cover.1706863981.git.perry.yuan@amd.com>
 <7ff16a39e508eeadf26afbffb2f621de180bcde8.1706863981.git.perry.yuan@amd.com>
From: Mario Limonciello <mario.limonciello@amd.com>
In-Reply-To: <7ff16a39e508eeadf26afbffb2f621de180bcde8.1706863981.git.perry.yuan@amd.com>
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On 2/2/2024 02:55, Perry Yuan wrote:
> to be more clear what is wrong with CPPC when pstate driver failed to
> load which has dependency on the CPPC capabilities.
> 
> Add one more debug message to notify user if CPPC is not supported by
> the CPU, then it will be easy to find out what need to fix for pstate
> driver loading issue.
> 
> [    0.477523] amd_pstate: the _CPC object is not present in SBIOS or ACPI disabled
> 
> Above message is not clear enough to verify whether CPPC is not supported.
> 
> Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
>   drivers/acpi/cppc_acpi.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index a50e70abdf19..e23a84f4a50a 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -679,8 +679,10 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
>   
>   	if (!osc_sb_cppc2_support_acked) {
>   		pr_debug("CPPC v2 _OSC not acked\n");
> -		if (!cpc_supported_by_cpu())
> +		if (!cpc_supported_by_cpu()) {
> +			pr_debug("CPPC is not supported by the CPU\n");
>   			return -ENODEV;
> +		}
>   	}
>   
>   	/* Parse the ACPI _CPC table for this CPU. */