ath9k_hw: warn if we cannot change the power to the chip

Suspend requires the device to be in fullsleep otherwise upon
resume the device becomes unresponsive. We need to ensure
that when we want the device to go to sleep it yields to
the request, otherwise we'll have a useless devices upon
resume. Warn when changing the power fails as we need
to look into these issues.

Cc: Paul Stewart <pstew@google.com>
Cc: Amod Bodas <amod.bodas@atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index 9f4398c..516227f 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1608,6 +1608,13 @@
 	}
 	ah->power_mode = mode;
 
+	/*
+	 * XXX: If this warning never comes up after a while then
+	 * simply keep the ATH_DBG_WARN_ON_ONCE() but make
+	 * ath9k_hw_setpower() return type void.
+	 */
+	ATH_DBG_WARN_ON_ONCE(!status);
+
 	return status;
 }
 EXPORT_SYMBOL(ath9k_hw_setpower);