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>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 736d456..826b6e1 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -199,6 +199,10 @@
 			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