Patch "Input: ALPS - fix TrackStick detection on Thinkpad L570 and Latitude 7370" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

Input: ALPS - fix TrackStick detection on Thinkpad L570 and Latitude 7370

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
input-alps-fix-trackstick-detection-on-thinkpad-l570-and-latitude-7370.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Masaki Ota <[email protected]>
Date: Mon, 29 Jan 2018 14:36:54 -0800
Subject: Input: ALPS - fix TrackStick detection on Thinkpad L570 and Latitude 7370

From: Masaki Ota <[email protected]>

commit 567b9b549cfa1cbc202762ae97b5385c29ade1e3 upstream.

The primary interface for the touchpad device in Thinkpad L570 is SMBus, so ALPS overlooked PS2 interface Firmware setting of TrackStick, and shipped with TrackStick otp bit is disabled.

The address 0xD7 contains device number information, so we can identify the device by checking this value, but to access it we need to enable Command mode, and then re-enable the device. Devices shipped in Thinkpad L570 report either 0x0C or 0x1D as device numbers, if we see them we assume that the devices are DualPoints.

The same issue exists on Dell Latitude 7370.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196929

---
 drivers/input/mouse/alps.c |   24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

@@ -2538,13 +2538,31 @@ static int alps_update_btn_info_ss4_v2(u
 }
 
 static int alps_update_dual_info_ss4_v2(unsigned char otp[][4],
-				       struct alps_data *priv)
+					struct alps_data *priv,
+					struct psmouse *psmouse)
 {
 	bool is_dual = false;
+	int reg_val = 0;
+	struct ps2dev *ps2dev = &psmouse->ps2dev;
 
-	if (IS_SS4PLUS_DEV(priv->dev_id))
+	if (IS_SS4PLUS_DEV(priv->dev_id)) {
 		is_dual = (otp[0][0] >> 4) & 0x01;
 
+		if (!is_dual) {
+			/* For support TrackStick of Thinkpad L/E series */
+			if (alps_exit_command_mode(psmouse) == 0 &&
+				alps_enter_command_mode(psmouse) == 0) {
+				reg_val = alps_command_mode_read_reg(psmouse,
+									0xD7);
+			}
+			alps_exit_command_mode(psmouse);
+			ps2_command(ps2dev, NULL, PSMOUSE_CMD_ENABLE);
+
+			if (reg_val == 0x0C || reg_val == 0x1D)
+				is_dual = true;
+		}
+	}
+
 	if (is_dual)
 		priv->flags |= ALPS_DUALPOINT |
 					ALPS_DUALPOINT_WITH_PRESSURE;

@@ -2567,7 +2585,7 @@ static int alps_set_defaults_ss4_v2(stru
 
 	alps_update_btn_info_ss4_v2(otp, priv);
 
-	alps_update_dual_info_ss4_v2(otp, priv);
+	alps_update_dual_info_ss4_v2(otp, priv, psmouse);
 
 	return 0;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/input-alps-fix-trackstick-detection-on-thinkpad-l570-and-latitude-7370.patch