linux-kernel - [PATCH 2/2] cpufreq: intel_pstate: enable HWP after resumed

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Message-Id: <7ddf56d88ed43701cd498fd42d1ae75e4eea1340.1517192577.git.yu.c.chen@intel.com>
Date:   Mon, 29 Jan 2018 10:27:57 +0800
From:   Yu Chen <yu.c.chen@...el.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yu Chen <yu.c.chen@...el.com>
Subject: [PATCH 2/2] cpufreq: intel_pstate: enable HWP after resumed

When maxcpus=1 is appended the BP is responsible
for re-enabling the HWP - because currently only
the APs invoke intel_pstate_hwp_enable() during
their online process - which might put the system
into unstable state after resume.

Fix this by enabling the HWP explicitly on BP during
resume.

Reported-by: Doug Smythies <dsmythies@...us.net>
Suggested-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Signed-off-by: Yu Chen <yu.c.chen@...el.com>
---
 drivers/cpufreq/intel_pstate.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 93a0e88bef76..89f637e8439c 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -779,6 +779,8 @@ static int intel_pstate_hwp_save_state(struct cpufreq_policy *policy)
 	return 0;
 }
 
+static void intel_pstate_hwp_enable(struct cpudata *cpudata);
+
 static int intel_pstate_resume(struct cpufreq_policy *policy)
 {
 	if (!hwp_active)
@@ -786,6 +788,8 @@ static int intel_pstate_resume(struct cpufreq_policy *policy)
 
 	mutex_lock(&intel_pstate_limits_lock);
 
+	if (!policy->cpu)
+		intel_pstate_hwp_enable(all_cpu_data[policy->cpu]);
 	all_cpu_data[policy->cpu]->epp_policy = 0;
 	intel_pstate_hwp_set(policy->cpu);
 
-- 
2.13.6