[3.13.y.z extended stable] Patch "cpufreq: intel_pstate: Reflect current no_turbo state correctly" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    cpufreq: intel_pstate: Reflect current no_turbo state correctly

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.11.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 2f9cb6eb6a2acf63cf13a4c557e7e9c46cc93b52 Mon Sep 17 00:00:00 2001
From: Gabriele Mazzotta <gabriele.mzt at gmail.com>
Date: Mon, 13 Oct 2014 08:37:41 -0700
Subject: cpufreq: intel_pstate: Reflect current no_turbo state correctly

commit 4521e1a0ce173daa23dfef8312d09051e057ff8e upstream.

Some BIOSes modify the state of MSR_IA32_MISC_ENABLE_TURBO_DISABLE
based on the current power source for the system battery AC vs
battery. Reflect the correct current state and ability to modify the
no_turbo sysfs file based on current state of
MSR_IA32_MISC_ENABLE_TURBO_DISABLE.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=83151
Signed-off-by: Gabriele Mazzotta <gabriele.mzt at gmail.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie at intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/cpufreq/intel_pstate.c | 49 +++++++++++++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 12 deletions(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index d21cd02..7d622cd 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -143,6 +143,7 @@ struct perf_limits {

 static struct perf_limits limits = {
 	.no_turbo = 0,
+	.turbo_disabled = 0,
 	.max_perf_pct = 100,
 	.max_perf = int_tofp(1),
 	.min_perf_pct = 0,
@@ -227,6 +228,18 @@ static inline void intel_pstate_reset_all_pid(void)
 	}
 }

+static inline void update_turbo_state(void)
+{
+	u64 misc_en;
+	struct cpudata *cpu;
+
+	cpu = all_cpu_data[0];
+	rdmsrl(MSR_IA32_MISC_ENABLE, misc_en);
+	limits.turbo_disabled =
+		(misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE ||
+		 cpu->pstate.max_pstate == cpu->pstate.turbo_pstate);
+}
+
 /************************** debugfs begin ************************/
 static int pid_param_set(void *data, u64 val)
 {
@@ -283,6 +296,20 @@ static void intel_pstate_debug_expose_params(void)
 		return sprintf(buf, "%u\n", limits.object);		\
 	}

+static ssize_t show_no_turbo(struct kobject *kobj,
+			     struct attribute *attr, char *buf)
+{
+	ssize_t ret;
+
+	update_turbo_state();
+	if (limits.turbo_disabled)
+		ret = sprintf(buf, "%u\n", limits.turbo_disabled);
+	else
+		ret = sprintf(buf, "%u\n", limits.no_turbo);
+
+	return ret;
+}
+
 static ssize_t store_no_turbo(struct kobject *a, struct attribute *b,
 				const char *buf, size_t count)
 {
@@ -291,11 +318,14 @@ static ssize_t store_no_turbo(struct kobject *a, struct attribute *b,
 	ret = sscanf(buf, "%u", &input);
 	if (ret != 1)
 		return -EINVAL;
-	limits.no_turbo = clamp_t(int, input, 0 , 1);
+
+	update_turbo_state();
 	if (limits.turbo_disabled) {
 		pr_warn("Turbo disabled by BIOS or unavailable on processor\n");
-		limits.no_turbo = limits.turbo_disabled;
+		return -EPERM;
 	}
+	limits.no_turbo = clamp_t(int, input, 0, 1);
+
 	return count;
 }

@@ -328,7 +358,6 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
 	return count;
 }

-show_one(no_turbo, no_turbo);
 show_one(max_perf_pct, max_perf_pct);
 show_one(min_perf_pct, min_perf_pct);

@@ -503,7 +532,8 @@ static void intel_pstate_get_min_max(struct cpudata *cpu, int *min, int *max)
 	int max_perf = cpu->pstate.turbo_pstate;
 	int max_perf_adj;
 	int min_perf;
-	if (limits.no_turbo)
+
+	if (limits.no_turbo || limits.turbo_disabled)
 		max_perf = cpu->pstate.max_pstate;

 	max_perf_adj = fp_toint(mul_fp(int_tofp(max_perf), limits.max_perf));
@@ -519,6 +549,8 @@ static void intel_pstate_set_pstate(struct cpudata *cpu, int pstate)
 {
 	int max_perf, min_perf;

+	update_turbo_state();
+
 	intel_pstate_get_min_max(cpu, &min_perf, &max_perf);

 	pstate = clamp_t(int, pstate, min_perf, max_perf);
@@ -736,7 +768,7 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
 		limits.max_policy_pct = 100;
 		limits.max_perf_pct = 100;
 		limits.max_perf = int_tofp(1);
-		limits.no_turbo = limits.turbo_disabled;
+		limits.no_turbo = 0;
 		return 0;
 	}
 	limits.min_perf_pct = (policy->min * 100) / policy->cpuinfo.max_freq;
@@ -776,7 +808,6 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
 {
 	struct cpudata *cpu;
 	int rc;
-	u64 misc_en;

 	rc = intel_pstate_init_cpu(policy->cpu);
 	if (rc)
@@ -784,12 +815,6 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy)

 	cpu = all_cpu_data[policy->cpu];

-	rdmsrl(MSR_IA32_MISC_ENABLE, misc_en);
-	if (misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE ||
-		cpu->pstate.max_pstate == cpu->pstate.turbo_pstate) {
-		limits.turbo_disabled = 1;
-		limits.no_turbo = 1;
-	}
 	if (limits.min_perf_pct == 100 && limits.max_perf_pct == 100)
 		policy->policy = CPUFREQ_POLICY_PERFORMANCE;
 	else
--
1.9.1