PM / domains: Add pd_ignore_unused to keep power domains enabled

Keep all power-domains already enabled by bootloader on, even if no
driver has claimed them. This is useful for debug and development, but
should not be needed on a platform with proper driver support.

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index bc34785..d4aff40 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2558,6 +2558,13 @@
 
 	pcmv=		[HW,PCMCIA] BadgePAD 4
 
+	pd_ignore_unused
+			[PM]
+			Keep all power-domains already enabled by bootloader on,
+			even if no driver has claimed them. This is useful
+			for debug and development, but should not be
+			needed on a platform with proper driver support.
+
 	pd.		[PARIDE]
 			See Documentation/blockdev/paride.txt.