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

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Message-ID: <20250826052747.2240670-1-superm1@kernel.org>
Date: Tue, 26 Aug 2025 00:27:47 -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 (AMD)" <superm1@...nel.org>
Subject: [PATCH] cpufreq/amd-pstate: Fix a regression leading to EPP 0 after resume

During the suspend sequence the cached CPPC request is destroyed
with the expectation that it's restored during resume.  This assumption
broke when the separate cache EPP variable was removed, and then it was
broken again by commit 608a76b65288 ("cpufreq/amd-pstate: Add support
for the "Requested CPU Min frequency" BIOS option") which explicitly
set it to zero during suspend.

Remove the invalidation and set the value during the suspend call to
update limits so that the cached variable can be used to restore on
resume.

Fixes: 608a76b65288 ("cpufreq/amd-pstate: Add support for the "Requested CPU Min frequency" BIOS option")
Fixes: b7a41156588a ("cpufreq/amd-pstate: Invalidate cppc_req_cached during suspend")
Closes: https://community.frame.work/t/increased-power-usage-after-resuming-from-suspend-on-ryzen-7040-kernel-6-15-regression/
Signed-off-by: Mario Limonciello (AMD) <superm1@...nel.org>
---
 drivers/cpufreq/amd-pstate.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index bbc27ef9edf7b..8eca4707226b8 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1626,13 +1626,14 @@ static int amd_pstate_suspend(struct cpufreq_policy *policy)
 	 * min_perf value across kexec reboots. If this CPU is just resumed back without kexec,
 	 * the limits, epp and desired perf will get reset to the cached values in cpudata struct
 	 */
-	ret = amd_pstate_update_perf(policy, perf.bios_min_perf, 0U, 0U, 0U, false);
+	ret = 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);
 	if (ret)
 		return ret;
 
-	/* invalidate to ensure it's rewritten during resume */
-	cpudata->cppc_req_cached = 0;
-
 	/* set this flag to avoid setting core offline*/
 	cpudata->suspended = true;
 
-- 
2.43.0