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>

1 files changed, 14 insertions, 9 deletions

diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 78e4de42efaa..52c9ebf94729 100644
--- 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;
         }