[PATCH 4.9 044/144] mfd: cros_ec: Fail early if we cannot identify the EC

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vincent Palatin <vpalatin@xxxxxxxxxxxx>

[ Upstream commit 0dbbf25561b29ffab5ba6277429760abdf49ceff ]

If we cannot communicate with the EC chip to detect the protocol version
and its features, it's very likely useless to continue. Else we will
commit all kind of uninformed mistakes (using the wrong protocol, the
wrong buffer size, mixing the EC with other chips).

Signed-off-by: Vincent Palatin <vpalatin@xxxxxxxxxxxx>
Acked-by: Benson Leung <bleung@xxxxxxxxxxxx>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
Reviewed-by: Gwendal Grignou <gwendal@xxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/mfd/cros_ec.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -86,7 +86,11 @@ int cros_ec_register(struct cros_ec_devi
 
 	mutex_init(&ec_dev->lock);
 
-	cros_ec_query_all(ec_dev);
+	err = cros_ec_query_all(ec_dev);
+	if (err) {
+		dev_err(dev, "Cannot identify the EC: error %d\n", err);
+		return err;
+	}
 
 	if (ec_dev->irq) {
 		err = request_threaded_irq(ec_dev->irq, NULL, ec_irq_thread,