ACPI: allow a native cpuidle driver to displace ACPI

The ACPI driver would fail probe when it found that
another driver had previously registered with cpuidle.

But this is a natural situation, as a native hardware
cpuidle driver should be able to bind instead of ACPI,
and the ACPI processor driver should be able to handle
yielding control of C-states while still handling
P-states and T-states.

Add a KERN_DEBUG line showing when acpi_idle
does successfully register.

Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 5675d9747e87..deefa8591746 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -616,7 +616,8 @@ static int __cpuinit acpi_processor_add(struct acpi_device *device)
         acpi_processor_get_limit_info(pr);
 
 
-        acpi_processor_power_init(pr, device);
+        if (cpuidle_get_driver() == &acpi_idle_driver)
+                acpi_processor_power_init(pr, device);
 
         pr->cdev = thermal_cooling_device_register("Processor", device,
                                                 &processor_cooling_ops);
@@ -920,9 +921,10 @@ static int __init acpi_processor_init(void)
         if (!acpi_processor_dir)
                 return -ENOMEM;
 #endif
-        result = cpuidle_register_driver(&acpi_idle_driver);
-        if (result < 0)
-                goto out_proc;
+
+        if (!cpuidle_register_driver(&acpi_idle_driver))
+                printk(KERN_DEBUG "ACPI: %s registered with cpuidle\n",
+                        acpi_idle_driver.name);
 
         result = acpi_bus_register_driver(&acpi_processor_driver);
         if (result < 0)
@@ -941,7 +943,6 @@ static int __init acpi_processor_init(void)
 out_cpuidle:
         cpuidle_unregister_driver(&acpi_idle_driver);
 
-out_proc:
 #ifdef CONFIG_ACPI_PROCFS
         remove_proc_entry(ACPI_PROCESSOR_CLASS, acpi_root_dir);
 #endif