Char: moxa, fix and optimise empty timer

moxa, fix and optimise empty timer

don't wait and delete empty timer in empty timer function. Also fire next
empty timer at rounded jiffies to save power.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/moxa.c

@@ -1040,14 +1040,14 @@ static void check_xmit_empty(unsigned long data)
 	struct moxa_port *ch;
 
 	ch = (struct moxa_port *) data;
-	del_timer_sync(&moxa_ports[ch->port].emptyTimer);
 	if (ch->tty && (ch->statusflags & EMPTYWAIT)) {
 		if (MoxaPortTxQueue(ch->port) == 0) {
 			ch->statusflags &= ~EMPTYWAIT;
 			tty_wakeup(ch->tty);
 			return;
 		}
-		mod_timer(&moxa_ports[ch->port].emptyTimer, jiffies + HZ);
+		mod_timer(&moxa_ports[ch->port].emptyTimer,
+				round_jiffies(jiffies + HZ));
 	} else
 		ch->statusflags &= ~EMPTYWAIT;
 }