linux-kernel - [PATCH v13 7/9] cpufreq:amd-pstate: Cap the CPPC.max_perf to nominal

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Date: Sat, 22 Jun 2024 00:51:02 +0800
From: Perry Yuan <perry.yuan@....com>
To: <rafael.j.wysocki@...el.com>, <Mario.Limonciello@....com>,
	<viresh.kumar@...aro.org>, <gautham.shenoy@....com>
CC: <Alexander.Deucher@....com>, <Xinmei.Huang@....com>,
	<Xiaojian.Du@....com>, <Li.Meng@....com>, <linux-pm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH v13 7/9] cpufreq:amd-pstate: Cap the CPPC.max_perf to nominal_perf if CPB is off

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

When Core Performance Boost is disabled by the user, the
CPPC_REQ.max_perf should not exceed the nominal_perf since by definition
the frequencies between nominal_perf and the highest_perf are in the
boost range. Fix this in amd_pstate_update()

Acked-by: Huang Rui <ray.huang@....com>
Reviewed-by: Mario Limonciello <mario.limonciello@....com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@....com>
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 02767230524e..05e80d2f8803 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -529,6 +529,7 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
 	unsigned long max_freq;
 	struct cpufreq_policy *policy = cpufreq_cpu_get(cpudata->cpu);
 	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,
@@ -551,6 +552,10 @@ 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