input: Fix "psmouse: Lost sync" problem. It was really losing sync.

drivers/input/serio/i8042.c

@@ -379,9 +379,12 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 	unsigned int dfl;
 	int ret;
 
+	mod_timer(&i8042_timer, jiffies + I8042_POLL_PERIOD);
+
 	spin_lock_irqsave(&i8042_lock, flags);
 	str = i8042_read_status();
-	data = i8042_read_data();
+	if (str & I8042_STR_OBF)
+		data = i8042_read_data();
 	spin_unlock_irqrestore(&i8042_lock, flags);
 
 	if (~str & I8042_STR_OBF) {
@@ -432,7 +435,6 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 irq_ret:
 	ret = 1;
 out:
-	mod_timer(&i8042_timer, jiffies + I8042_POLL_PERIOD);
 	return IRQ_RETVAL(ret);
 }