Input: i8042 - i8042_flush fix for a full 8042 buffer

When 8042 internal data buffer is full, the driver
erroneously decides that the controller is not present.

i8042_flush returns the number of flushed bytes, which is
in 0 - I8042_BUFFER_SIZE range inclusive. Therefore, i8042_flush
has no way to indicate an error. Moreover i8042_controller_check
takes initially full buffer (i8042_flush returned
I8042_BUFFER_SIZE) as a sign of absence of the controller.

Let's change i8042 to return success/error instead and make sure
we do not return error prematurely.

Signed-off-by: Andrey Moiseev <o2g.org.ru@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 78e4de42efaacec53c29f740fafe490dead2af84..52c9ebf94729ff5bf6531cc7773902ece632d03b 100644 (file)
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -223,21 +223,26 @@ static int i8042_flush(void)
 {
        unsigned long flags;
        unsigned char data, str;
-       int i = 0;
+       int count = 0;
+       int retval = 0;
 
        spin_lock_irqsave(&i8042_lock, flags);
 
-       while (((str = i8042_read_status()) & I8042_STR_OBF) && (i < I8042_BUFFER_SIZE)) {
-               udelay(50);
-               data = i8042_read_data();
-               i++;
-               dbg("%02x <- i8042 (flush, %s)\n",
-                   data, str & I8042_STR_AUXDATA ? "aux" : "kbd");
+       while ((str = i8042_read_status()) & I8042_STR_OBF) {
+               if (count++ < I8042_BUFFER_SIZE) {
+                       udelay(50);
+                       data = i8042_read_data();
+                       dbg("%02x <- i8042 (flush, %s)\n",
+                           data, str & I8042_STR_AUXDATA ? "aux" : "kbd");
+               } else {
+                       retval = -EIO;
+                       break;
+               }
        }
 
        spin_unlock_irqrestore(&i8042_lock, flags);
 
-       return i;
+       return retval;
 }
 
 /*
@@ -849,7 +854,7 @@ static int __init i8042_check_aux(void)
 
 static int i8042_controller_check(void)
 {
-       if (i8042_flush() == I8042_BUFFER_SIZE) {
+       if (i8042_flush()) {
                pr_err("No controller found\n");
                return -ENODEV;
        }