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>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index b4749969c6b..e98071a6481 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/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;