3 files changed, 40 insertions, 10 deletions

diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
index 2679a165d399..ffdc82313192 100644
--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -270,7 +270,6 @@ static struct alps_model_info *alps_get_model(struct psmouse *psmouse, int *vers
 static int alps_passthrough_mode(struct psmouse *psmouse, int enable)
 {
         struct ps2dev *ps2dev = &psmouse->ps2dev;
-        unsigned char param[3];
         int cmd = enable ? PSMOUSE_CMD_SETSCALE21 : PSMOUSE_CMD_SETSCALE11;
 
         if (ps2_command(ps2dev, NULL, cmd) ||
@@ -280,7 +279,7 @@ static int alps_passthrough_mode(struct psmouse *psmouse, int enable)
                 return -1;
 
         /* we may get 3 more bytes, just ignore them */
-        ps2_command(ps2dev, param, 0x0300);
+        ps2_drain(ps2dev, 3, 100);
 
         return 0;
 }
diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
index c978657068c5..92b92ee03791 100644
--- a/drivers/input/serio/libps2.c
+++ b/drivers/input/serio/libps2.c
@@ -29,6 +29,7 @@ MODULE_LICENSE("GPL");
 
 EXPORT_SYMBOL(ps2_init);
 EXPORT_SYMBOL(ps2_sendbyte);
+EXPORT_SYMBOL(ps2_drain);
 EXPORT_SYMBOL(ps2_command);
 EXPORT_SYMBOL(ps2_schedule_command);
 EXPORT_SYMBOL(ps2_handle_ack);
@@ -45,11 +46,11 @@ struct ps2work {
 
 
 /*
- * ps2_sendbyte() sends a byte to the mouse, and waits for acknowledge.
- * It doesn't handle retransmission, though it could - because when there would
- * be need for retransmissions, the mouse has to be replaced anyway.
+ * ps2_sendbyte() sends a byte to the device and waits for acknowledge.
+ * It doesn't handle retransmission, though it could - because if there
+ * is a need for retransmissions device has to be replaced anyway.
  *
- * ps2_sendbyte() can only be called from a process context
+ * ps2_sendbyte() can only be called from a process context.
  */
 
 int ps2_sendbyte(struct ps2dev *ps2dev, unsigned char byte, int timeout)
@@ -72,6 +73,31 @@ int ps2_sendbyte(struct ps2dev *ps2dev, unsigned char byte, int timeout)
 }
 
 /*
+ * ps2_drain() waits for device to transmit requested number of bytes
+ * and discards them.
+ */
+
+void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
+{
+        if (maxbytes > sizeof(ps2dev->cmdbuf)) {
+                WARN_ON(1);
+                maxbytes = sizeof(ps2dev->cmdbuf);
+        }
+
+        down(&ps2dev->cmd_sem);
+
+        serio_pause_rx(ps2dev->serio);
+        ps2dev->flags = PS2_FLAG_CMD;
+        ps2dev->cmdcnt = maxbytes;
+        serio_continue_rx(ps2dev->serio);
+
+        wait_event_timeout(ps2dev->wait,
+                           !(ps2dev->flags & PS2_FLAG_CMD),
+                           msecs_to_jiffies(timeout));
+        up(&ps2dev->cmd_sem);
+}
+
+/*
  * ps2_command() sends a command and its parameters to the mouse,
  * then waits for the response and puts it in the param array.
  *
@@ -86,6 +112,11 @@ int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
         int rc = -1;
         int i;
 
+        if (receive > sizeof(ps2dev->cmdbuf)) {
+                WARN_ON(1);
+                return -1;
+        }
+
         down(&ps2dev->cmd_sem);
 
         serio_pause_rx(ps2dev->serio);
@@ -101,10 +132,9 @@ int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
          * ACKing the reset command, and so it can take a long
          * time before the ACK arrrives.
          */
-        if (command & 0xff)
-                if (ps2_sendbyte(ps2dev, command & 0xff,
-                        command == PS2_CMD_RESET_BAT ? 1000 : 200))
-                        goto out;
+        if (ps2_sendbyte(ps2dev, command & 0xff,
+                         command == PS2_CMD_RESET_BAT ? 1000 : 200))
+                goto out;
 
         for (i = 0; i < send; i++)
                 if (ps2_sendbyte(ps2dev, param[i], 200))
diff --git a/include/linux/libps2.h b/include/linux/libps2.h
index 923bdbc6d9e4..a710bddda4eb 100644
--- a/include/linux/libps2.h
+++ b/include/linux/libps2.h
@@ -41,6 +41,7 @@ struct ps2dev {
 
 void ps2_init(struct ps2dev *ps2dev, struct serio *serio);
 int ps2_sendbyte(struct ps2dev *ps2dev, unsigned char byte, int timeout);
+void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout);
 int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command);
 int ps2_schedule_command(struct ps2dev *ps2dev, unsigned char *param, int command);
 int ps2_handle_ack(struct ps2dev *ps2dev, unsigned char data);