Set userspace governor as default, which stays same effect
as when cpufreq in xen is not enabled. As a result, enable cpufreq
in xen by default to avoid reboot to activate cpufreq. Now it's
always on but w/o performance impact if user doesn't tempt
to change governor. We also add some warning info for debug.

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>

diff -r e9e46a38ac0d xen/arch/x86/acpi/cpufreq/cpufreq.c
--- a/xen/arch/x86/acpi/cpufreq/cpufreq.c	Fri Dec 19 15:09:33 2008 +0800
+++ b/xen/arch/x86/acpi/cpufreq/cpufreq.c	Fri Dec 19 18:40:32 2008 +0800
@@ -393,8 +393,10 @@ static int acpi_cpufreq_target(struct cp
 
     drv_write(&cmd);
 
-    if (!check_freqs(cmd.mask, freqs.new, data))
+    if (!check_freqs(cmd.mask, freqs.new, data)) {
+        printk(KERN_WARNING "Fail transfer to new freq %d\n", freqs.new);
         return -EAGAIN;
+    }
 
     for_each_cpu_mask(j, online_policy_cpus)
         cpufreq_statistic_update(j, perf->state, next_perf_state);
diff -r e9e46a38ac0d xen/common/domain.c
--- a/xen/common/domain.c	Fri Dec 19 15:09:33 2008 +0800
+++ b/xen/common/domain.c	Fri Dec 19 18:40:32 2008 +0800
@@ -32,13 +32,15 @@
 
 /* Linux config option: propageted to domain0 */
 /* xen_processor_pmbits: xen control Cx, Px, ... */
-unsigned int xen_processor_pmbits = 0;
+unsigned int xen_processor_pmbits = XEN_PROCESSOR_PM_PX;
 
 /* opt_dom0_vcpus_pin: If true, dom0 VCPUs are pinned. */
 static unsigned int opt_dom0_vcpus_pin;
 boolean_param("dom0_vcpus_pin", opt_dom0_vcpus_pin);
 
-enum cpufreq_controller cpufreq_controller;
+/* set Xen as default cpufreq */
+enum cpufreq_controller cpufreq_controller = FREQCTL_xen;
+
 static void __init setup_cpufreq_option(char *str)
 {
     if ( !strcmp(str, "dom0-kernel") )
@@ -46,11 +48,6 @@ static void __init setup_cpufreq_option(
         xen_processor_pmbits &= ~XEN_PROCESSOR_PM_PX;
         cpufreq_controller = FREQCTL_dom0_kernel;
         opt_dom0_vcpus_pin = 1;
-    }
-    else if ( !strcmp(str, "xen") )
-    {
-        xen_processor_pmbits |= XEN_PROCESSOR_PM_PX;
-        cpufreq_controller = FREQCTL_xen;
     }
 }
 custom_param("cpufreq", setup_cpufreq_option);
diff -r e9e46a38ac0d xen/drivers/cpufreq/utility.c
--- a/xen/drivers/cpufreq/utility.c	Fri Dec 19 15:09:33 2008 +0800
+++ b/xen/drivers/cpufreq/utility.c	Fri Dec 19 18:40:32 2008 +0800
@@ -360,10 +360,14 @@ int __cpufreq_set_policy(struct cpufreq_
         /* start new governor */
         data->governor = policy->governor;
         if (__cpufreq_governor(data, CPUFREQ_GOV_START)) {
+            printk(KERN_WARNING "Fail change to %s governor\n",
+                                 data->governor->name);
             /* new governor failed, so re-start old one */
             if (old_gov) {
                 data->governor = old_gov;
                 __cpufreq_governor(data, CPUFREQ_GOV_START);
+                printk(KERN_WARNING "Still stay at %s governor\n",
+                                     data->governor->name);
             }
             return -EINVAL;
         }
diff -r e9e46a38ac0d xen/include/acpi/cpufreq/cpufreq.h
--- a/xen/include/acpi/cpufreq/cpufreq.h	Fri Dec 19 15:09:33 2008 +0800
+++ b/xen/include/acpi/cpufreq/cpufreq.h	Fri Dec 19 18:40:32 2008 +0800
@@ -10,6 +10,9 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+
+#ifndef __XEN_CPUFREQ_PM_H__
+#define __XEN_CPUFREQ_PM_H__
 
 #include <xen/types.h>
 #include <xen/list.h>
@@ -91,7 +94,7 @@ extern int cpufreq_register_governor(str
 extern int cpufreq_register_governor(struct cpufreq_governor *governor);
 extern int cpufreq_unregister_governor(struct cpufreq_governor *governor);
 extern struct cpufreq_governor *__find_governor(const char *governor);
-#define CPUFREQ_DEFAULT_GOVERNOR &cpufreq_gov_performance
+#define CPUFREQ_DEFAULT_GOVERNOR &cpufreq_gov_userspace
 
 /* pass a target to the cpufreq driver */
 extern int __cpufreq_driver_target(struct cpufreq_policy *policy,
@@ -218,3 +221,4 @@ int get_cpufreq_ondemand_para(uint32_t *
                               uint32_t *up_threshold);
 int write_ondemand_sampling_rate(unsigned int sampling_rate);
 int write_ondemand_up_threshold(unsigned int up_threshold);
+#endif /* __XEN_CPUFREQ_PM_H__ */