linux-kernel - [PATCH v4 04/13] cpufreq: amd-pstate: prefetch cppc_req_cached value in amd_pstate_cpu

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Message-ID: <686bc72b4dc3a663c00126c852e3b4774a280700.1657876961.git.Perry.Yuan@amd.com>
Date:   Fri, 15 Jul 2022 06:04:23 -0400
From:   Perry Yuan <Perry.Yuan@....com>
To:     <rafael.j.wysocki@...el.com>, <viresh.kumar@...aro.org>,
        <Ray.Huang@....com>
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>,
        <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Perry Yuan <Perry.Yuan@....com>
Subject: [PATCH v4 04/13] 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.The cached values are read through MSR interface, so here use
shared_mem flag to check the registers are accessible

Also the core performance boost state will be initialized through
hardware configuration register

* shared_mem flag is used for the shared memory type CPPC implementation
  which dose not support MSR interface operation

Signed-off-by: Perry Yuan <Perry.Yuan@....com>
---
 drivers/cpufreq/amd-pstate.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 43e6df9f67f6..d8c4153dbe4f 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -92,6 +92,8 @@ struct amd_aperf_mperf {
  * @prev: Last Aperf/Mperf/tsc count value read from register
  * @freq: current cpu frequency value
  * @boost_supported: check whether the Processor or SBIOS supports boost mode
+ * @precision_boost_off: the core performance boost disabled state
+ * @cppc_hw_conf_cached: the cached hardware configuration register
  *
  * The amd_cpudata is key private data for each CPU thread in AMD P-State, and
  * represents all the attributes and goals that AMD P-State requests at runtime.
@@ -117,6 +119,7 @@ struct amd_cpudata {
 
 	u64 freq;
 	bool	boost_supported;
+	bool	precision_boost_off;
 	u64 	cppc_hw_conf_cached;
 };
 
@@ -547,12 +550,17 @@ 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;
+		cpudata->precision_boost_off = value & AMD_CPPC_PRECISION_BOOST_ENABLED;
 
-	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;
-- 
2.32.0