acpi-cpufreq: Add quirk to disable _PSD usage on all AMD CPUs

To workaround some Windows specific behavior, the ACPI _PSD table
on AMD desktop boards advertises all cores as dependent, meaning
that they all can only use the same P-state. acpi-cpufreq strictly
obeys this description, instantiating one CPU only and symlinking
the others. But the hardware can have distinct frequencies for each
core and powernow-k8 did it that way.
So, in order to use the hardware to its full potential and keep the
original powernow-k8 behavior, lets override the _PSD table setting
on AMD hardware.
We use the siblings table, as it matches the current hardware
behavior.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 067a61f06bb5dd075300b6d159104cac03506f9a..70e717305c2957f27f401d80555c9ae60e93531f 100644 (file)
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -51,6 +51,8 @@ MODULE_AUTHOR("Paul Diefenbaugh, Dominik Brodowski");
 MODULE_DESCRIPTION("ACPI Processor P-States Driver");
 MODULE_LICENSE("GPL");
 
+#define PFX "acpi-cpufreq: "
+
 enum {
        UNDEFINED_CAPABLE = 0,
        SYSTEM_INTEL_MSR_CAPABLE,
@@ -586,6 +588,14 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
                policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
                cpumask_copy(policy->cpus, cpu_core_mask(cpu));
        }
+
+       if (check_amd_hwpstate_cpu(cpu) && !acpi_pstate_strict) {
+               cpumask_clear(policy->cpus);
+               cpumask_set_cpu(cpu, policy->cpus);
+               cpumask_copy(policy->related_cpus, cpu_sibling_mask(cpu));
+               policy->shared_type = CPUFREQ_SHARED_TYPE_HW;
+               pr_info_once(PFX "overriding BIOS provided _PSD data\n");
+       }
 #endif
 
        /* capability check */