cpufreq: intel_pstate: Fix limits issue with operation mode switching

There is a problem with intel_pstate operation mode switching
introduced by commit fb1fe104 (cpufreq: intel_pstate: Operation
mode control from sysfs), because the global sysfs limits are
preserved across operation modes while per-policy limits are
reinitialized from scratch on a mode switch and both sets of limits
may get out of sync this way.

Fix that by always reinitializing the global limits upon the
registration of the driver.

Fixes: fb1fe104 (cpufreq: intel_pstate: Operation mode control from sysfs)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

drivers/cpufreq/intel_pstate.c

@@ -364,37 +364,25 @@ static bool driver_registered __read_mostly;
 static bool acpi_ppc;
 #endif
 
-static struct perf_limits performance_limits = {
-	.no_turbo = 0,
-	.turbo_disabled = 0,
-	.max_perf_pct = 100,
-	.max_perf = int_ext_tofp(1),
-	.min_perf_pct = 100,
-	.min_perf = int_ext_tofp(1),
-	.max_policy_pct = 100,
-	.max_sysfs_pct = 100,
-	.min_policy_pct = 0,
-	.min_sysfs_pct = 0,
-};
+static struct perf_limits performance_limits;
+static struct perf_limits powersave_limits;
+static struct perf_limits *limits;
 
-static struct perf_limits powersave_limits = {
-	.no_turbo = 0,
-	.turbo_disabled = 0,
-	.max_perf_pct = 100,
-	.max_perf = int_ext_tofp(1),
-	.min_perf_pct = 0,
-	.min_perf = 0,
-	.max_policy_pct = 100,
-	.max_sysfs_pct = 100,
-	.min_policy_pct = 0,
-	.min_sysfs_pct = 0,
-};
+static void intel_pstate_init_limits(struct perf_limits *limits)
+{
+	memset(limits, 0, sizeof(*limits));
+	limits->max_perf_pct = 100;
+	limits->max_perf = int_ext_tofp(1);
+	limits->max_policy_pct = 100;
+	limits->max_sysfs_pct = 100;
+}
 
-#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE
-static struct perf_limits *limits = &performance_limits;
-#else
-static struct perf_limits *limits = &powersave_limits;
-#endif
+static void intel_pstate_set_performance_limits(struct perf_limits *limits)
+{
+	intel_pstate_init_limits(limits);
+	limits->min_perf_pct = 100;
+	limits->min_perf = int_ext_tofp(1);
+}
 
 static DEFINE_MUTEX(intel_pstate_driver_lock);
 static DEFINE_MUTEX(intel_pstate_limits_lock);
@@ -2084,20 +2072,6 @@ static void intel_pstate_clear_update_util_hook(unsigned int cpu)
 	synchronize_sched();
 }
 
-static void intel_pstate_set_performance_limits(struct perf_limits *limits)
-{
-	limits->no_turbo = 0;
-	limits->turbo_disabled = 0;
-	limits->max_perf_pct = 100;
-	limits->max_perf = int_ext_tofp(1);
-	limits->min_perf_pct = 100;
-	limits->min_perf = int_ext_tofp(1);
-	limits->max_policy_pct = 100;
-	limits->max_sysfs_pct = 100;
-	limits->min_policy_pct = 0;
-	limits->min_sysfs_pct = 0;
-}
-
 static void intel_pstate_update_perf_limits(struct cpufreq_policy *policy,
 					    struct perf_limits *limits)
 {
@@ -2466,6 +2440,11 @@ static int intel_pstate_register_driver(void)
 {
 	int ret;
 
+	intel_pstate_init_limits(&powersave_limits);
+	intel_pstate_set_performance_limits(&performance_limits);
+	limits = IS_ENABLED(CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE) ?
+			&performance_limits : &powersave_limits;
+
 	ret = cpufreq_register_driver(intel_pstate_driver);
 	if (ret) {
 		intel_pstate_driver_cleanup();