1 files changed, 15 insertions, 1 deletions

diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
index 23da96e57b1..19f6b9d27e8 100644
--- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
+++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
@@ -33,7 +33,7 @@
 #include <linux/cpufreq.h>
 #include <linux/compiler.h>
 #include <linux/dmi.h>
-#include <linux/ftrace.h>
+#include <trace/power.h>
 
 #include <linux/acpi.h>
 #include <linux/io.h>
@@ -72,6 +72,8 @@ struct acpi_cpufreq_data {
 
 static DEFINE_PER_CPU(struct acpi_cpufreq_data *, drv_data);
 
+DEFINE_TRACE(power_mark);
+
 /* acpi_perf_data is a pointer to percpu data. */
 static struct acpi_processor_performance *acpi_perf_data;
 
@@ -680,6 +682,18 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
                             perf->states[i].transition_latency * 1000;
         }
 
+        /* Check for high latency (>20uS) from buggy BIOSes, like on T42 */
+        if (perf->control_register.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE &&
+            policy->cpuinfo.transition_latency > 20 * 1000) {
+                static int print_once;
+                policy->cpuinfo.transition_latency = 20 * 1000;
+                if (!print_once) {
+                        print_once = 1;
+                        printk(KERN_INFO "Capping off P-state tranision latency"
+                                " at 20 uS\n");
+                }
+        }
+
         data->max_freq = perf->states[0].core_frequency * 1000;
         /* table init */
         for (i = 0; i < perf->state_count; i++) {