[PATCH] input: cros_ec_keyb: fix button/switch capability reports

[Brian Norris]

The cros_ec_keyb_bs array lists buttons and switches together, expecting
that its users will match the appropriate type and bit fields. But
cros_ec_keyb_register_bs() only checks the 'bit' field, which causes
misreported input capabilities in some cases. For example, tablets
(e.g., Scarlet -- a.k.a. Acer Chromebook Tab 10) were reporting a SW_LID
capability, because EC_MKBP_POWER_BUTTON and EC_MKBP_LID_OPEN happen to
share the same bit.

(This has comedic effect on a tablet, in which a power-management daemon
then thinks this "lid" is closed, and so puts the system to sleep as
soon as it boots!)

To fix this, check both the 'ev_type' and 'bit' fields before reporting
the capability.

Tested with a lid (Kevin / Samsung Chromebook Plus) and without a lid
(Scarlet / Acer Chromebook Tab 10).

This error got introduced when porting the feature from the downstream
Chromium OS kernel to be upstreamed.

Fixes: cdd7950e7aa4 ("input: cros_ec_keyb: Add non-matrix buttons and switches")
Cc: <stable@xxxxxxxxxxxxxxx>
Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
Cc: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
---
 drivers/input/keyboard/cros_ec_keyb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
index 81be6f781f0b..d56001181598 100644
--- a/drivers/input/keyboard/cros_ec_keyb.c
+++ b/drivers/input/keyboard/cros_ec_keyb.c
@@ -493,7 +493,8 @@ static int cros_ec_keyb_register_bs(struct cros_ec_keyb *ckdev)
 	for (i = 0; i < ARRAY_SIZE(cros_ec_keyb_bs); i++) {
 		const struct cros_ec_bs_map *map = &cros_ec_keyb_bs[i];
 
-		if (buttons & BIT(map->bit))
+		if ((map->ev_type == EV_KEY && (buttons & BIT(map->bit))) ||
+		    (map->ev_type == EV_SW && (switches & BIT(map->bit))))
 			input_set_capability(idev, map->ev_type, map->code);
 	}
 
-- 
2.19.1.930.g4563a0d9d0-goog