[PATCH v2 1/4] ACPI: processor: Reorder acpi_processor_driver_init()

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

The cpufreq policy notifier in the ACPI processor driver may as
well be registered before the driver itself, which causes
acpi_processor_cpufreq_init to be true (unless the notifier
registration fails, which is unlikely at that point) when the
ACPI CPU thermal cooling devices are registered, so the
processor_get_max_state() result does not change while
acpi_processor_driver_init() is running.

Change the ordering in acpi_processor_driver_init() accordingly
to prevent the max_state value from remaining 0 permanently for all
ACPI CPU cooling devices due to setting acpi_processor_cpufreq_init
too late.  [Note that processor_get_max_state() may still return
different values at different times after this change, depending on
the cpufreq driver registration time, but that issue needs to be
addressed separately.]

Fixes: a365105c685c("thermal: sysfs: Reuse cdev->max_state")
Reported-by: Wang, Quanxian <quanxian.wang@xxxxxxxxx>
Link: https://lore.kernel.org/linux-pm/53ec1f06f61c984100868926f282647e57ecfb2d.camel@xxxxxxxxx/
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---

v1 -> v2: Expand changelog to explain that this particular patch addresses
          part of the issue.

---
 drivers/acpi/processor_driver.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Index: linux-pm/drivers/acpi/processor_driver.c
===================================================================
--- linux-pm.orig/drivers/acpi/processor_driver.c
+++ linux-pm/drivers/acpi/processor_driver.c
@@ -263,6 +263,12 @@ static int __init acpi_processor_driver_
 	if (acpi_disabled)
 		return 0;
 
+	if (!cpufreq_register_notifier(&acpi_processor_notifier_block,
+				       CPUFREQ_POLICY_NOTIFIER)) {
+		acpi_processor_cpufreq_init = true;
+		acpi_processor_ignore_ppc_init();
+	}
+
 	result = driver_register(&acpi_processor_driver);
 	if (result < 0)
 		return result;
@@ -276,12 +282,6 @@ static int __init acpi_processor_driver_
 	cpuhp_setup_state_nocalls(CPUHP_ACPI_CPUDRV_DEAD, "acpi/cpu-drv:dead",
 				  NULL, acpi_soft_cpu_dead);
 
-	if (!cpufreq_register_notifier(&acpi_processor_notifier_block,
-				       CPUFREQ_POLICY_NOTIFIER)) {
-		acpi_processor_cpufreq_init = true;
-		acpi_processor_ignore_ppc_init();
-	}
-
 	acpi_processor_throttling_init();
 	return 0;
 err: