linux-kernel - Re: [PATCH] cpufreq/amd-pstate: Fix a regression leading to EPP 0 after hibernate

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Message-ID: <aOc2BcT9NUCO8HJp@BLRRASHENOY1.amd.com>
Date: Thu, 9 Oct 2025 09:41:49 +0530
From: "Gautham R. Shenoy" <gautham.shenoy@....com>
To: "Mario Limonciello (AMD)" <superm1@...nel.org>
Cc: Perry Yuan <perry.yuan@....com>,
	"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <linux-kernel@...r.kernel.org>,
	"open list:CPU FREQUENCY SCALING FRAMEWORK" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] cpufreq/amd-pstate: Fix a regression leading to EPP 0
 after hibernate

On Tue, Sep 23, 2025 at 10:29:29AM -0500, Mario Limonciello (AMD) wrote:
> After resuming from S4, all CPUs except the boot CPU have the wrong EPP
> hint programmed.  This is because when the CPUs were offlined the EPP value
> was reset to 0.
> 
> This is a similar problem as fixed by
> commit ba3319e590571 ("cpufreq/amd-pstate: Fix a regression leading to EPP
> 0 after resume") and the solution is also similar.  When offlining rather
> than reset the values to zero, reset them to match those chosen by the
> policy. When the CPUs are onlined again these values will be restored.
> 
> Closes: https://community.frame.work/t/increased-power-usage-after-resuming-from-suspend-on-ryzen-7040-kernel-6-15-regression/74531/20?u=mario_limonciello
> Fixes: 608a76b65288 ("cpufreq/amd-pstate: Add support for the "Requested CPU Min frequency" BIOS option")
> Signed-off-by: Mario Limonciello (AMD) <superm1@...nel.org>

Apologies for the delay in reviewing this.

The fix looks good to me.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@....com>

-- 
Thanks and Regards
gautham.


> ---
>  drivers/cpufreq/amd-pstate.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 9f3b9dc26ab5..ba2adea03db1 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1617,7 +1617,11 @@ static int amd_pstate_cpu_offline(struct cpufreq_policy *policy)
>  	 * min_perf value across kexec reboots. If this CPU is just onlined normally after this, the
>  	 * limits, epp and desired perf will get reset to the cached values in cpudata struct
>  	 */
> -	return amd_pstate_update_perf(policy, perf.bios_min_perf, 0U, 0U, 0U, false);
> +	return amd_pstate_update_perf(policy, perf.bios_min_perf,
> +				     FIELD_GET(AMD_CPPC_DES_PERF_MASK, cpudata->cppc_req_cached),
> +				     FIELD_GET(AMD_CPPC_MAX_PERF_MASK, cpudata->cppc_req_cached),
> +				     FIELD_GET(AMD_CPPC_EPP_PERF_MASK, cpudata->cppc_req_cached),
> +				     false);
>  }
>  
>  static int amd_pstate_suspend(struct cpufreq_policy *policy)
> -- 
> 2.51.0
>