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authorAndi Kleen <ak@linux.intel.com>2012-01-26 00:09:08 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2012-01-26 16:48:12 -0800
commit9061e0e16700ef228837e96987ff51794c956197 (patch)
tree53d2ffa0fbc64f404848f4bfeb964d84cf08de36 /drivers/acpi/processor_perflib.c
parentb66b8b9a4a79087dde1b358a016e5c8739ccf186 (diff)
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>
Diffstat (limited to 'drivers/acpi/processor_perflib.c')
-rw-r--r--drivers/acpi/processor_perflib.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 85b32376dad7..0af48a8554cd 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -240,6 +240,28 @@ void acpi_processor_ppc_exit(void)
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;