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Subject[PATCH 26/85] ACPI: cpufreq, processor: Detect old BIOS, not supporting CPU freq on a recent CPU.
From: Thomas Renninger <trenn@suse.de>

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>
---
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 80c251e..242f814 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)
--
1.5.5.1


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