3 files changed, 64 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index d533c205eea4..3509ca04b5bb 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1073,6 +1073,46 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
 		}
 	}
 
+	/*
+	 * Sometimes boot loaders set CPU frequency to a value outside of
+	 * frequency table present with cpufreq core. In such cases CPU might be
+	 * unstable if it has to run on that frequency for long duration of time
+	 * and so its better to set it to a frequency which is specified in
+	 * freq-table. This also makes cpufreq stats inconsistent as
+	 * cpufreq-stats would fail to register because current frequency of CPU
+	 * isn't found in freq-table.
+	 *
+	 * Because we don't want this change to effect boot process badly, we go
+	 * for the next freq which is >= policy->cur ('cur' must be set by now,
+	 * otherwise we will end up setting freq to lowest of the table as 'cur'
+	 * is initialized to zero).
+	 *
+	 * We are passing target-freq as "policy->cur - 1" otherwise
+	 * __cpufreq_driver_target() would simply fail, as policy->cur will be
+	 * equal to target-freq.
+	 */
+	if ((cpufreq_driver->flags & CPUFREQ_NEED_INITIAL_FREQ_CHECK)
+	    && has_target()) {
+		/* Are we running at unknown frequency ? */
+		ret = cpufreq_frequency_table_get_index(policy, policy->cur);
+		if (ret == -EINVAL) {
+			/* Warn user and fix it */
+			pr_warn("%s: CPU%d: Running at unlisted freq: %u KHz\n",
+				__func__, policy->cpu, policy->cur);
+			ret = __cpufreq_driver_target(policy, policy->cur - 1,
+				CPUFREQ_RELATION_L);
+
+			/*
+			 * Reaching here after boot in a few seconds may not
+			 * mean that system will remain stable at "unknown"
+			 * frequency for longer duration. Hence, a BUG_ON().
+			 */
+			BUG_ON(ret);
+			pr_warn("%s: CPU%d: Unlisted initial frequency changed to: %u KHz\n",
+				__func__, policy->cpu, policy->cur);
+		}
+	}
+
 	/* related cpus should atleast have policy->cpus */
 	cpumask_or(policy->related_cpus, policy->related_cpus, policy->cpus);
 
diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
index 3458d27f63b4..a8ac0427fbfe 100644
--- a/drivers/cpufreq/freq_table.c
+++ b/drivers/cpufreq/freq_table.c
@@ -178,7 +178,29 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 }
 EXPORT_SYMBOL_GPL(cpufreq_frequency_table_target);
 
+int cpufreq_frequency_table_get_index(struct cpufreq_policy *policy,
+		unsigned int freq)
+{
+	struct cpufreq_frequency_table *table;
+	int i;
+
+	table = cpufreq_frequency_get_table(policy->cpu);
+	if (unlikely(!table)) {
+		pr_debug("%s: Unable to find frequency table\n", __func__);
+		return -ENOENT;
+	}
+
+	for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
+		if (table[i].frequency == freq)
+			return i;
+	}
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(cpufreq_frequency_table_get_index);
+
 static DEFINE_PER_CPU(struct cpufreq_frequency_table *, cpufreq_show_table);
+
 /**
  * show_available_freqs - show available frequencies for the specified CPU
  */
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 91b8c84e8cd0..aaf800eb9dd2 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -450,6 +450,8 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 				   unsigned int target_freq,
 				   unsigned int relation,
 				   unsigned int *index);
+int cpufreq_frequency_table_get_index(struct cpufreq_policy *policy,
+		unsigned int freq);
 
 void cpufreq_frequency_table_update_policy_cpu(struct cpufreq_policy *policy);
 ssize_t cpufreq_show_cpus(const struct cpumask *mask, char *buf);