ACPI: Load acpi-cpufreq from processor driver automatically
The only left over hole in automatic cpufreq driver loading was the loading
of ACPI cpufreq. This driver should be loaded when ACPI supports a _PDC
method and the CPU vendor wants to use acpi cpufreq.
Simply add a request module call to the acpi processor core driver
when this is true. This seems like the simplest solution for this.
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 85b3237..0af48a8 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -240,6 +240,28 @@
acpi_processor_ppc_status &= ~PPC_REGISTERED;
}
+/*
+ * Do a quick check if the systems looks like it should use ACPI
+ * cpufreq. We look at a _PCT method being available, but don't
+ * do a whole lot of sanity checks.
+ */
+void acpi_processor_load_module(struct acpi_processor *pr)
+{
+ static int requested;
+ acpi_status status = 0;
+ struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+
+ if (!arch_has_acpi_pdc() || requested)
+ return;
+ status = acpi_evaluate_object(pr->handle, "_PCT", NULL, &buffer);
+ if (!ACPI_FAILURE(status)) {
+ printk(KERN_INFO PREFIX "Requesting acpi_cpufreq\n");
+ request_module_nowait("acpi_cpufreq");
+ requested = 1;
+ }
+ kfree(buffer.pointer);
+}
+
static int acpi_processor_get_performance_control(struct acpi_processor *pr)
{
int result = 0;