ACPI: cpufreq, processor: Detect old BIOS, not supporting CPU freq on a recent CPU.

On Intel CPUs it is rather common and a good hint that BIOSes which do provide
_PPC func, but not the frequencies itself in _PSS function, are old and need
to be updated for CPU freq support.

Tell the user/vendor he has a BIOS/firmware problem.
Make use of FW_BUG interface to give vendors and users the ability to
automatically check with (or let linuxfirmwarekit do that):
dmesg |grep "Firmware Bug"

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 80c251ec6d2a..242f8143008a 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -38,6 +38,7 @@
 
 #include <asm/uaccess.h>
 #endif
+#include <asm/cpufeature.h>
 
 #include <acpi/acpi_bus.h>
 #include <acpi/processor.h>
@@ -334,7 +335,6 @@ static int acpi_processor_get_performance_info(struct acpi_processor *pr)
         acpi_status status = AE_OK;
         acpi_handle handle = NULL;
 
-
         if (!pr || !pr->performance || !pr->handle)
                 return -EINVAL;
 
@@ -347,13 +347,25 @@ static int acpi_processor_get_performance_info(struct acpi_processor *pr)
 
         result = acpi_processor_get_performance_control(pr);
         if (result)
-                return result;
+                goto update_bios;
 
         result = acpi_processor_get_performance_states(pr);
         if (result)
-                return result;
+                goto update_bios;
 
         return 0;
+
+        /*
+         * Having _PPC but missing frequencies (_PSS, _PCT) is a very good hint that
+         * the BIOS is older than the CPU and does not know its frequencies
+         */
+ update_bios:
+        if (ACPI_SUCCESS(acpi_get_handle(pr->handle, "_PPC", &handle))){
+                if(boot_cpu_has(X86_FEATURE_EST))
+                        printk(KERN_WARNING FW_BUG "BIOS needs update for CPU "
+                               "frequency support\n");
+        }
+        return result;
 }
 
 int acpi_processor_notify_smm(struct module *calling_module)