[PATCH] alps: Fix left touchpad button getting stuck when using it with trackpoint

From: Hans de Goede
Date: Wed Apr 08 2015 - 10:21:40 EST

When the left touchpad button gets pressed, and then the trackpoint is moved,
and then the button is released, the following happens:

1) touchpad packet is received, touchpad evdev node reports BTN_LEFT 1
2) pointingstick packet is received, the hw will report a BTN_LEFT 1 in this
packet because when the trackstick is active it communicates the combined
touchpad + pointingstick buttons in the trackstick packet, since
alps_report_bare_ps2_packet passes NULL (*) for the dev2 parameter to
alps_report_buttons the combining is not detected and the pointingstick
evdev node will also report BTN_LEFT 1
3) on release of the button a pointingstick packet with BTN_LEFT 0 is received,
and the pointingstick evdev node will report BTN_LEFT 0

Note how because of the passing as NULL for dev2 the touchpad evdev node
will never send BTN_LEFT 0 in this scenario leading to a stuck mouse button.

This is a regression in 4.0 introduced by commit 04aae283ba6a8
("Input: ALPS - do not mix trackstick and external PS/2 mouse data")

This commit fixes this by passing in the touchpad evdev as dev2 parameter
when calling alps_report_buttons for the pointingstick on alps v2 devices,
so that alps_report_buttons correctly detect that we're already reporting the
button as pressed via the touchpad evdev node, and will also send the release
event there.

Reported-by: Hans de Bruin <jmdebruin@xxxxxxxxx>
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
drivers/input/mouse/alps.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
index 80b6eca..6962c26 100644
--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -1159,13 +1159,14 @@ static void alps_report_bare_ps2_packet(struct psmouse *psmouse,
bool report_buttons)
struct alps_data *priv = psmouse->private;
- struct input_dev *dev;
+ struct input_dev *dev, *dev2 = NULL;

/* Figure out which device to use to report the bare packet */
if (priv->proto_version == ALPS_PROTO_V2 &&
(priv->flags & ALPS_DUALPOINT)) {
/* On V2 devices the DualPoint Stick reports bare packets */
dev = priv->dev2;
+ dev2 = psmouse->dev;
} else if (unlikely(IS_ERR_OR_NULL(priv->dev3))) {
/* Register dev3 mouse if we received PS/2 packet first time */
if (!IS_ERR(priv->dev3))
@@ -1177,7 +1178,7 @@ static void alps_report_bare_ps2_packet(struct psmouse *psmouse,

if (report_buttons)
- alps_report_buttons(dev, NULL,
+ alps_report_buttons(dev, dev2,
packet[0] & 1, packet[0] & 2, packet[0] & 4);

input_report_rel(dev, REL_X,

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/