[v3] Input: alps - Don't handle ALPS cs19 trackpoint-only device

Commit Message

Hui Wang June 17, 2019, 10:13 a.m. UTC

On a latest Lenovo laptop, the trackpoint and 3 buttons below it
don't work at all, when we move the trackpoint or press those 3
buttons, the kernel will print out:
"Rejected trackstick packet from non DualPoint device"

This device is identified as alps touchpad but the packet has
trackpoint format, so the alps.c drops the packet and prints out
the message above.

According to XiaoXiao's explanation, this device is named cs19 and
is trackpoint-only device, its firmware is only for trackpoint, it
is independent of touchpad and is a completely different device from
DualPoint ones.

To drive this device with mininal changes to the existing driver, we
just let the alps driver not handle this device, then the trackpoint.c
will be the driver of this device.

With the trackpoint.c, this trackpoint and 3 buttons all work well,
they have all features that the trackpoint should have, like
scrolling-screen, drag-and-drop and frame-selection.

Signed-off-by: XiaoXiao Liu <[e-mail]>
Signed-off-by: Hui Wang <[e-mail]>
---
 drivers/input/mouse/alps.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

Patch

diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
index 0a6f7ca883e7..548012e6d316 100644
--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -24,6 +24,7 @@ 
 
 #include "psmouse.h"
 #include "alps.h"
+#include "trackpoint.h"
 
 /*
  * Definitions for ALPS version 3 and 4 command mode protocol
@@ -2864,6 +2865,23 @@  static const struct alps_protocol_info *alps_match_table(unsigned char *e7,
 	return NULL;
 }
 
+static bool alps_is_cs19_trackpoint(struct psmouse *psmouse)
+{
+	u8 param[2] = { 0 };
+
+	if (ps2_command(&psmouse->ps2dev,
+			param, MAKE_PS2_CMD(0, 2, TP_READ_ID)))
+		return false;
+
+	if (param[0] == TP_VARIANT_ALPS) {
+		psmouse_warn(psmouse,
+			     "It is an ALPS trackpoint-only device (CS19), make sure the MOUSE_PS2_TRACKPOINT is enabled to drive it\n");
+		return true;
+	}
+
+	return false;
+}
+
 static int alps_identify(struct psmouse *psmouse, struct alps_data *priv)
 {
 	const struct alps_protocol_info *protocol;
@@ -3164,6 +3182,17 @@  int alps_detect(struct psmouse *psmouse, bool set_properties)
 	if (error)
 		return error;
 
+	/*
+	 * ALPS cs19 is a trackpoint-only device, it is completely independent
+	 * of touchpad. So it is a different device from DualPoint ones, if it
+	 * is identified as a cs19 trackpoint device, we return -EINVAL here and
+	 * let trackpoint.c to drive this device.
+	 * If ps2_command() fails here, we depend on the immediate followed
+	 * psmouse_reset() to reset the device to normal state.
+	 */
+	if (alps_is_cs19_trackpoint(psmouse))
+		return -EINVAL;
+
 	/*
 	 * Reset the device to make sure it is fully operational:
 	 * on some laptops, like certain Dell Latitudes, we may