[PATCH v2] Input: cros-ec-keyb: Only register keyboard if rows/columns exist

[Stephen Boyd]

If the device is a detachable, we may still probe this device because
there are some button switches, e.g. volume buttons and power buttons,
registered by this driver. Let's allow the device node to be missing row
and column device properties to indicate that the keyboard matrix
shouldn't be registered. This removes an input device on Trogdor devices
such as Wormdingler that don't have a matrix keyboard, but still have
power and volume buttons. That helps userspace understand there isn't
a keyboard present when the detachable keyboard is disconnected.

Cc: Benson Leung <bleung@xxxxxxxxxxxx>
Cc: Guenter Roeck <groeck@xxxxxxxxxxxx>
Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
Cc: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
---

Changes from v1 (https://lore.kernel.org/r/20220413033334.1514008-1-swboyd@xxxxxxxxxxxx):
 * Use device_property_present

 drivers/input/keyboard/cros_ec_keyb.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
index 6534dfca60b4..ceb23e2e0d94 100644
--- a/drivers/input/keyboard/cros_ec_keyb.c
+++ b/drivers/input/keyboard/cros_ec_keyb.c
@@ -537,6 +537,15 @@ static int cros_ec_keyb_register_matrix(struct cros_ec_keyb *ckdev)
 	u32 key_pos;
 	unsigned int row, col, scancode, n_physmap;
 
+	/*
+	 * No rows and columns? There isn't a matrix but maybe there are
+	 * switches to register in cros_ec_keyb_register_bs() because this is a
+	 * detachable device.
+	 */
+	if (!device_property_present(dev, "keypad,num-rows") &&
+	    !device_property_present(dev, "keypad,num-cols"))
+		return 0;
+
 	err = matrix_keypad_parse_properties(dev, &ckdev->rows, &ckdev->cols);
 	if (err)
 		return err;

base-commit: 3123109284176b1532874591f7c81f3837bbdc17
-- 
https://chromeos.dev