ACPI: processor: add kernel command line support for early _PDC eval

Allow platforms not listed in DMI table
to opt-in and evaluate _PDC early.

Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 11 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 736d45602886..826b6e148316 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -199,6 +199,10 @@ and is between 256 and 4096 characters. It is defined in the file
                         acpi_display_output=video
                         See above.
 
+        acpi_early_pdc_eval     [HW,ACPI] Evaluate processor _PDC methods
+                                early. Needed on some platforms to properly
+                                initialize the EC.
+
         acpi_irq_balance [HW,ACPI]
                         ACPI will balance active IRQs
                         default in APIC mode
diff --git a/drivers/acpi/processor_pdc.c b/drivers/acpi/processor_pdc.c
index 7247819dbd80..3bbafe9576ae 100644
--- a/drivers/acpi/processor_pdc.c
+++ b/drivers/acpi/processor_pdc.c
@@ -151,6 +151,13 @@ static int set_early_pdc_optin(const struct dmi_system_id *id)
         return 0;
 }
 
+static int param_early_pdc_optin(char *s)
+{
+        early_pdc_optin = 1;
+        return 1;
+}
+__setup("acpi_early_pdc_eval", param_early_pdc_optin);
+
 static struct dmi_system_id __cpuinitdata early_pdc_optin_table[] = {
         {
         set_early_pdc_optin, "HP Envy", {