cpufreq acpi: only call _PPC after cpufreq ACPI init funcs got called already

Ingo Molnar provided a fix to not call _PPC at processor driver
initialization time in "[PATCH] ACPI: fix cpufreq regression" (git
commit e4233dec749a3519069d9390561b5636a75c7579)

But it can still happen that _PPC is called at processor driver
initialization time.

This patch should make sure that this is not possible anymore.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/powerpc/platforms/cell/cbe_cpufreq_pmi.c

@@ -96,6 +96,12 @@ static int pmi_notifier(struct notifier_block *nb,
 	struct cpufreq_frequency_table *cbe_freqs;
 	u8 node;
 
+	/* Should this really be called for CPUFREQ_ADJUST, CPUFREQ_INCOMPATIBLE
+	 * and CPUFREQ_NOTIFY policy events?)
+	 */
+	if (event == CPUFREQ_START)
+		return 0;
+
 	cbe_freqs = cpufreq_frequency_get_table(policy->cpu);
 	node = cbe_cpu_to_node(policy->cpu);
 

drivers/acpi/processor_perflib.c

@@ -64,7 +64,13 @@ static DEFINE_MUTEX(performance_mutex);
  * policy is adjusted accordingly.
  */
 
-static unsigned int ignore_ppc = 0;
+/* ignore_ppc:
+ * -1 -> cpufreq low level drivers not initialized -> _PSS, etc. not called yet
+ *       ignore _PPC
+ *  0 -> cpufreq low level drivers initialized -> consider _PPC values
+ *  1 -> ignore _PPC totally -> forced by user through boot param
+ */
+static unsigned int ignore_ppc = -1;
 module_param(ignore_ppc, uint, 0644);
 MODULE_PARM_DESC(ignore_ppc, "If the frequency of your machine gets wrongly" \
 		 "limited by BIOS, this should help");
@@ -72,7 +78,7 @@ MODULE_PARM_DESC(ignore_ppc, "If the frequency of your machine gets wrongly" \
 #define PPC_REGISTERED   1
 #define PPC_IN_USE       2
 
-static int acpi_processor_ppc_status = 0;
+static int acpi_processor_ppc_status;
 
 static int acpi_processor_ppc_notifier(struct notifier_block *nb,
 				       unsigned long event, void *data)
@@ -81,6 +87,11 @@ static int acpi_processor_ppc_notifier(struct notifier_block *nb,
 	struct acpi_processor *pr;
 	unsigned int ppc = 0;
 
+	if (event == CPUFREQ_START && ignore_ppc <= 0) {
+		ignore_ppc = 0;
+		return 0;
+	}
+
 	if (ignore_ppc)
 		return 0;
 

drivers/cpufreq/cpufreq.c

@@ -825,6 +825,9 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
 	policy->user_policy.min = policy->cpuinfo.min_freq;
 	policy->user_policy.max = policy->cpuinfo.max_freq;
 
+	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+				     CPUFREQ_START, policy);
+
 #ifdef CONFIG_SMP
 
 #ifdef CONFIG_HOTPLUG_CPU

include/linux/cpufreq.h

@@ -106,6 +106,7 @@ struct cpufreq_policy {
 #define CPUFREQ_ADJUST		(0)
 #define CPUFREQ_INCOMPATIBLE	(1)
 #define CPUFREQ_NOTIFY		(2)
+#define CPUFREQ_START		(3)
 
 #define CPUFREQ_SHARED_TYPE_NONE (0) /* None */
 #define CPUFREQ_SHARED_TYPE_HW	 (1) /* HW does needed coordination */