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

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Message-ID: <20250923152929.1306578-1-superm1@kernel.org>
Date: Tue, 23 Sep 2025 10:29:29 -0500
From: "Mario Limonciello (AMD)" <superm1@...nel.org>
To: "Gautham R . Shenoy" <gautham.shenoy@....com>
Cc: Perry Yuan <perry.yuan@....com>,
	linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	linux-pm@...r.kernel.org (open list:CPU FREQUENCY SCALING FRAMEWORK),
	Mario Limonciello <superm1@...nel.org>
Subject: [PATCH] cpufreq/amd-pstate: Fix a regression leading to EPP 0 after hibernate

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>
---
 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