linux-kernel - [PATCH v6 4/6] cpufreq: amd-pstate: fix the MSR highest perf will be reset issue while cpb boost off

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Message-ID: <8e04afd3f5f8f9f9aa1a4b7954ad4b8946d11d31.1710754236.git.perry.yuan@amd.com>
Date: Mon, 18 Mar 2024 18:11:11 +0800
From: Perry Yuan <perry.yuan@....com>
To: <rafael.j.wysocki@...el.com>, <Mario.Limonciello@....com>,
	<viresh.kumar@...aro.org>, <Ray.Huang@....com>, <gautham.shenoy@....com>,
	<Borislav.Petkov@....com>
CC: <Alexander.Deucher@....com>, <Xinmei.Huang@....com>,
	<oleksandr@...alenko.name>, <Xiaojian.Du@....com>, <Li.Meng@....com>,
	<linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v6 4/6] cpufreq: amd-pstate: fix the MSR highest perf will be reset issue while cpb boost off

From: Perry Yuan <Perry.Yuan@....com>

Select the min perf to fix the highest perf value while update pstate
CPPC request MSR register, here we need to limit the max perf value when
CPU boost is disabled in case of that highest perf value in the MSR will be
reset to original highest perf value which cause the BOOST control
failed.

Signed-off-by: Perry Yuan <Perry.Yuan@....com>
---
 drivers/cpufreq/amd-pstate.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 4cd2818045c7..513f91611cd5 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -476,6 +476,7 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
 			      u32 des_perf, u32 max_perf, bool fast_switch, int gov_flags)
 {
 	u64 prev = READ_ONCE(cpudata->cppc_req_cached);
+	u32 nominal_perf = READ_ONCE(cpudata->nominal_perf);
 	u64 value = prev;
 
 	min_perf = clamp_t(unsigned long, min_perf, cpudata->min_limit_perf,
@@ -495,6 +496,10 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
 	value &= ~AMD_CPPC_DES_PERF(~0L);
 	value |= AMD_CPPC_DES_PERF(des_perf);
 
+	/* limit the max perf when core performance boost feature is disabled */
+	if (!amd_pstate_global_params.cpb_boost)
+		max_perf = min_t(unsigned long, nominal_perf, max_perf);
+
 	value &= ~AMD_CPPC_MAX_PERF(~0L);
 	value |= AMD_CPPC_MAX_PERF(max_perf);
 
-- 
2.34.1