staging: unisys: visorbus: add comment to explain polling logic in controlvm_periodic_work

Added a comment to explain polling frequency variation logic in
controlvm_periodic_logic() in visorchipset.c.

Signed-off-by: Sameer Wadgaonkar <sameer.wadgaonkar@unisys.com>
Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/visorbus/visorchipset.c

@@ -1787,6 +1787,11 @@ controlvm_periodic_work(struct work_struct *work)
 	/* parahotplug_worker */
 	parahotplug_process_list();
 
+/*
+ * The controlvm messages are sent in a bulk. If we start receiving messages, we
+ * want the polling to be fast. If we do not receive any message for
+ * MIN_IDLE_SECONDS, we can slow down the polling.
+ */
 schedule_out:
 	if (time_after(jiffies, chipset_dev->most_recent_message_jiffies +
 				(HZ * MIN_IDLE_SECONDS))) {