linux-kernel - [PATCH 04/12] cpufreq: amd-pstate: prefetch cppc_req_cached value in amd_pstate_cpu

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Date:   Thu, 7 Jul 2022 12:59:08 -0400
From:   Perry Yuan <Perry.Yuan@....com>
To:     <rafael.j.wysocki@...el.com>, <viresh.kumar@...aro.org>,
        <Ray.Huang@....com>, Huang Rui <ray.huang@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <Deepak.Sharma@....com>, <Mario.Limonciello@....com>,
        <Nathan.Fontenot@....com>, <Alexander.Deucher@....com>,
        <Jinzhou.Su@....com>, <Xinmei.Huang@....com>,
        <Xiaojian.Du@....com>, <Li.Meng@....com>,
        Perry Yuan <Perry.Yuan@....com>
Subject: [PATCH 04/12] cpufreq: amd-pstate: prefetch cppc_req_cached value in amd_pstate_cpu_init()

This cppc_req_cached valued should be prefetched during
amd_pstate_cpu_init call period, then the amd_pstate_update() will get
correct cached value before updating the perf to change the cpu perf
level.

Signed-off-by: Perry Yuan <Perry.Yuan@....com>
---
 drivers/cpufreq/amd-pstate.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 43e6df9f67f6..e4904da54541 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -547,12 +547,17 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
 	cpudata->lowest_nonlinear_freq = lowest_nonlinear_freq;
 
 	policy->driver_data = cpudata;
+	if (!shared_mem) {
+		ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_HW_CTL, &value);
+		if (ret)
+			return ret;
+		WRITE_ONCE(cpudata->cppc_hw_conf_cached, value);
 
-	ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_HW_CTL, &value);
-	if (ret)
-		return ret;
-	WRITE_ONCE(cpudata->cppc_hw_conf_cached, value);
-
+		ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, &value);
+		if (ret)
+			return ret;
+		WRITE_ONCE(cpudata->cppc_req_cached, value);
+	}
 	amd_pstate_boost_init(cpudata);
 
 	return 0;
-- 
2.25.1