CHROMIUM: atkbd: workaround for ChromeOS EC keyboard enable bug

The ChromeOS EC enables keystrokes too early, and the driver
can get scancodes when it's expecting a response from the
GETID request.  The workaround consists of repeating the request
a few times if it fails.

BUG=chrome-os-partner:17005
TEST=verified that the workaround works around the bug
BRANCH=none

Signed-off-by: Luigi Semenzato <semenzato@chromium.org>
Change-Id: Ica4ad7ed1564c07ab196b302d1a33732a48c680f
Reviewed-on: https://gerrit.chromium.org/gerrit/43165
Commit-Queue: Trond Wuellner <trond@chromium.org>
Reviewed-by: Trond Wuellner <trond@chromium.org>
Tested-by: Trond Wuellner <trond@chromium.org>

diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c
index 916b994a20807ecea95f6fb43e6e91750ed0b669..41ebfeeda9c3c67bd92fe5a1cb44335b2e3aa0e1 100644 (file)
--- a/drivers/input/keyboard/atkbd.c
+++ b/drivers/input/keyboard/atkbd.c
@@ -684,6 +684,7 @@ static int atkbd_probe(struct atkbd *atkbd)
 {
        struct ps2dev *ps2dev = &atkbd->ps2dev;
        unsigned char param[2];
+       int getid_attempts_left = 5;
 
 /*
  * Some systems, where the bit-twiddling when testing the io-lines of the
@@ -704,8 +705,16 @@ static int atkbd_probe(struct atkbd *atkbd)
  * should make sure we don't try to set the LEDs on it.
  */
 
+/* Chrome OS workaround only: we have a bug in the EC that causes keystrokes to
+ * be enabled too early, so we may read scancodes instead of the GETID
+ * response.  In that case, instead of failing, retry a few times.
+ */
+
+getid_retry:
+       getid_attempts_left--;
        param[0] = param[1] = 0xa5;     /* initialize with invalid values */
        if (ps2_command(ps2dev, param, ATKBD_CMD_GETID)) {
+               dev_warn(&ps2dev->serio->dev, "GETID failed");
 
 /*
  * If the get ID command failed, we check if we can at least set the LEDs on
@@ -713,14 +722,24 @@ static int atkbd_probe(struct atkbd *atkbd)
  * the LEDs off, which we want anyway.
  */
                param[0] = 0;
-               if (ps2_command(ps2dev, param, ATKBD_CMD_SETLEDS))
-                       return -1;
+               if (ps2_command(ps2dev, param, ATKBD_CMD_SETLEDS)) {
+                       dev_warn(&ps2dev->serio->dev, "atkbd: SETLEDS failed");
+                       if (getid_attempts_left <= 0)
+                               return -1;
+                       else
+                               goto getid_retry;
+               }
                atkbd->id = 0xabba;
                return 0;
        }
 
-       if (!ps2_is_keyboard_id(param[0]))
-               return -1;
+       if (!ps2_is_keyboard_id(param[0])) {
+               dev_warn(&ps2dev->serio->dev, "bad keyboard id %d", param[0]);
+               if (getid_attempts_left <= 0)
+                       return -1;
+               else
+                       goto getid_retry;
+       }
 
        atkbd->id = (param[0] << 8) | param[1];
 
@@ -1162,6 +1181,7 @@ static int atkbd_connect(struct serio *serio, struct serio_driver *drv)
        if (atkbd->write) {
 
                if (atkbd_probe(atkbd)) {
+                       dev_err(&serio->dev, "probe failed");
                        err = -ENODEV;
                        goto fail3;
                }
@@ -1223,8 +1243,10 @@ static int atkbd_reconnect(struct serio *serio)
        atkbd_disable(atkbd);
 
        if (atkbd->write) {
-               if (atkbd_probe(atkbd))
+               if (atkbd_probe(atkbd)) {
+                       dev_err(&serio->dev, "reconnect: probe failed");
                        goto out;
+               }
 
                if (atkbd->set != atkbd_select_set(atkbd, atkbd->set, atkbd->extra))
                        goto out;