linux-kernel - [PATCH 4.0 REGRESSION FIX] alps: Fix left touchpad button getting stuck when using it with trackpoint

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Date:	Wed,  8 Apr 2015 17:38:52 +0200
From:	Hans de Goede <hdegoede@...hat.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Hans de Bruin <jmdebruin@...net.nl>,
	Pali Rohár <pali.rohar@...il.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Hans de Goede <hdegoede@...hat.com>
Subject: [PATCH 4.0 REGRESSION FIX] alps: Fix left touchpad button getting stuck when using it with trackpoint

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@...net.nl>
Signed-off-by: Hans de Goede <hdegoede@...hat.com>
---
 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,
-- 
2.3.4

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