[CPUFREQ] Only check for transition latency on problematic governors (kconfig fix)

Cc: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Jones <davej@redhat.com>

2 files changed, 22 insertions, 8 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 418522f88f7..65ac5851122 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1484,17 +1484,30 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,
                                         unsigned int event)
 {
         int ret;
-        struct cpufreq_governor *gov = CPUFREQ_PERFORMANCE_GOVERNOR;
+
+        /* Only must be defined when default governor is known to have latency
+           restrictions, like e.g. conservative or ondemand.
+           That this is the case is already ensured in Kconfig
+        */
+#ifdef CONFIG_CPU_FREQ_GOV_PERFORMANCE
+        struct cpufreq_governor *gov = &cpufreq_gov_performance;
+#else
+        struct cpufreq_governor *gov = NULL;
+#endif
 
         if (policy->governor->max_transition_latency &&
             policy->cpuinfo.transition_latency >
             policy->governor->max_transition_latency) {
-                printk(KERN_WARNING "%s governor failed, too long"
-                       " transition latency of HW, fallback"
-                       " to %s governor\n",
-                       policy->governor->name,
-                       gov->name);
-                       policy->governor = gov;
+                if (!gov)
+                        return -EINVAL;
+                else {
+                        printk(KERN_WARNING "%s governor failed, too long"
+                               " transition latency of HW, fallback"
+                               " to %s governor\n",
+                               policy->governor->name,
+                               gov->name);
+                        policy->governor = gov;
+                }
         }
 
         if (!try_module_get(policy->governor->owner))
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 9e5f5d0c87f..450a841b589 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -286,8 +286,9 @@ static inline unsigned int cpufreq_quick_get(unsigned int cpu)
   Performance governor is fallback governor if any other gov failed to
   auto load due latency restrictions
 */
+#ifdef CONFIG_CPU_FREQ_GOV_PERFORMANCE
 extern struct cpufreq_governor cpufreq_gov_performance;
-#define CPUFREQ_PERFORMANCE_GOVERNOR    (&cpufreq_gov_performance)
+#endif
 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE
 #define CPUFREQ_DEFAULT_GOVERNOR        (&cpufreq_gov_performance)
 #elif defined(CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE)