New: Intel Turbo can't be disabled/enabled under certain condictions

https://bugzilla.kernel.org/show_bug.cgi?id=83151

Bug ID: 83151
Summary: Intel Turbo can't be disabled/enabled under certain
condictions
Product: Power Management
Version: 2.5
Kernel Version: 3.16
Hardware: x86-64
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: cpufreq
Assignee: [email protected]
Reporter: [email protected]
Regression: No

On my laptop (Dell XPS 13 9333) MSR_IA32_MISC_ENABLE_TURBO_DISABLE is 0 when AC is present, 1 otherwise.
Because of this, setting turbo_disabled on init leads to some issues:
* If I turn on the laptop while the AC is present, the sysfs interface always allows me to change the state of no_turbo. However, the changes are only effective when the AC is present.
* If I turn on the laptop while on battery, the sysfs interface doesn't allow me to change the state of no_turbo. That means I'm not able to disable it when it's automatically enabled when I plug the AC.

Note that I don't have the possibility to disable Intel Turbo from the BIOS settings.

You are receiving this mail because:
You are the assignee for the bug.

https://bugzilla.kernel.org/show_bug.cgi?id=83151

--- Comment #1 from Gabriele Mazzotta <[email protected]> --- I also noticed that because of the changes of the turbo state not expected by intel_pstate, max_perf is sometimes wrong.

The patch should fix my problem. I don't know if there's a way to avoid reading the register every time or if there's a better way to deal with my problem.

index c5eac94..b8adfec 100644
@@ -218,6 +218,13 @@ static inline void intel_pstate_reset_all_pid(void)
     }
 }
 
+static int turbo_disabled(void) {
+    u64 misc_en;
+    rdmsrl(MSR_IA32_MISC_ENABLE, misc_en);
+    return (limits.turbo_disabled ||
+            (misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE));
+}
+
 /************************** debugfs begin ************************/
 static int pid_param_set(void *data, u64 val)
 {

@@ -284,10 +291,8 @@ static ssize_t store_no_turbo(struct kobject *a, struct

attribute *b,

     if (ret != 1)
         return -EINVAL;
     limits.no_turbo = clamp_t(int, input, 0 , 1);
-    if (limits.turbo_disabled) {
+    if (turbo_disabled())
         pr_warn("Turbo disabled by BIOS or unavailable on processor\n");
-        limits.no_turbo = limits.turbo_disabled;
-    }
     return count;

}

@@ -323,6 +328,12 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,

     return count;

}

+static ssize_t show_actual_no_turbo(struct kobject *kobj,
+ struct attribute *attr, char *buf)
+{
+ return sprintf(buf, "%u\n", limits.no_turbo || turbo_disabled());
+}
+
show_one(no_turbo, no_turbo); show_one(max_perf_pct, max_perf_pct); show_one(min_perf_pct, min_perf_pct);
@@ -330,11 +341,13 @@ show_one(min_perf_pct, min_perf_pct);
define_one_global_rw(no_turbo); define_one_global_rw(max_perf_pct); define_one_global_rw(min_perf_pct);
+define_one_global_ro(actual_no_turbo);

 static struct attribute *intel_pstate_attributes[] = {
     &no_turbo.attr,
     &max_perf_pct.attr,
     &min_perf_pct.attr,

+ &actual_no_turbo.attr,
NULL
};

@@ -386,7 +399,7 @@ static void byt_set_pstate(struct cpudata *cpudata, int pstate)

     u32 vid;

     val = pstate << 8;
-    if (limits.no_turbo && !limits.turbo_disabled)
+    if (limits.no_turbo && !turbo_disabled())
         val |= (u64)1 << 32;

     vid_fp = cpudata->vid.min + mul_fp(
@@ -454,7 +467,7 @@ static void core_set_pstate(struct cpudata *cpudata, int
pstate)
     u64 val;

     val = pstate << 8;
-    if (limits.no_turbo && !limits.turbo_disabled)
+    if (limits.no_turbo && !turbo_disabled())
         val |= (u64)1 << 32;

     wrmsrl_on_cpu(cpudata->cpu, MSR_IA32_PERF_CTL, val);
@@ -501,7 +514,7 @@ static void intel_pstate_get_min_max(struct cpudata *cpu,
int *min, int *max)
     int max_perf_adj;
     int min_perf;

- if (limits.no_turbo)
+ if (limits.no_turbo || turbo_disabled())

         max_perf = cpu->pstate.max_pstate;

     max_perf_adj = fp_toint(mul_fp(int_tofp(max_perf), limits.max_perf));
@@ -719,7 +732,6 @@ static int intel_pstate_set_policy(struct cpufreq_policy
*policy)
         limits.min_perf = int_tofp(1);
         limits.max_perf_pct = 100;
         limits.max_perf = int_tofp(1);
-        limits.no_turbo = limits.turbo_disabled;
         return 0;
     }
     limits.min_perf_pct = (policy->min * 100) / policy->cpuinfo.max_freq;
@@ -762,7 +774,6 @@ 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)

@@ -770,12 +781,8 @@ 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) {
+ if (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

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You are the assignee for the bug.

https://bugzilla.kernel.org/show_bug.cgi?id=83151

Dirk Brandewie <[email protected]> changed:

What |Removed |Added
----------------------------------------------------------------------------
CC| |[email protected]

--- Comment #2 from Dirk Brandewie <[email protected]> --- I am just back from vacation give me a couple of days to dig out of the inbox to review/test

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You are the assignee for the bug.

https://bugzilla.kernel.org/show_bug.cgi?id=83151

Lan Tianyu <[email protected]> changed:

What |Removed |Added
----------------------------------------------------------------------------

             Status|NEW                         |ASSIGNED
                 CC|                            |[email protected]
           Assignee|[email protected]     |[email protected]

You are receiving this mail because:
You are the assignee for the bug.