acpi-cpufreq: Do not load on K8

de3ed81d746d ("[CPUFREQ] Change link order of x86 cpufreq modules")
changed cpufreq drivers link order so that powernow-k8 gets loaded first
due to earlier K8s having BIOS bugs.

However, now that acpi-cpufreq supports both AMD and Intel CPUs with HW
P-states, we want to load it first, so that cases where acpi-cpufreq and
powernow-k8 are both built-in and powernow-k8 initializing first, can be
addressed.

So, make sure that even if acpi-cpufreq gets loaded first, it errors out
on K8s and powernow-k8 can be loaded then successfully.

Signed-off-by: Matthew Garrett <mjg59@srcf.ucam.org>
References: http://lkml.kernel.org/r/20130118162347.GA31499@srcf.ucam.org
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 7b0d49d78c61fc6c9fd312b0d05663ad42edf099..22f9b47c5c74d30eaee965f6ba746f524ad1a4b4 100644 (file)
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -762,6 +762,12 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
 
        switch (perf->control_register.space_id) {
        case ACPI_ADR_SPACE_SYSTEM_IO:
+               if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
+                   boot_cpu_data.x86 == 0xf) {
+                       pr_debug("AMD K8 systems must use native drivers.\n");
+                       result = -ENODEV;
+                       goto err_unreg;
+               }
                pr_debug("SYSTEM IO addr space\n");
                data->cpu_feature = SYSTEM_IO_CAPABLE;
                break;