[PATCH 3/3] CPUFREQ: processor.ko: Try to detect old BIOS, not supporting CPU freq on a recent CPU.

Thomas Renninger
2008-08-27T13:27:13Z

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 he has a BIOS/firmware problem.

Signed-off-by: Thomas Renninger <trenn@suse.de>
---
drivers/acpi/processor_perflib.c | 18 +++++++++++++++---
1 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 0133af4..3a2886f 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)
--
1.5.4.5