Patch "Input: trackpoint - force 3 buttons if 0 button is reported" has been added to the 4.4-stable tree

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

Input: trackpoint - force 3 buttons if 0 button is reported

to the 4.4-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-trackpoint-force-3-buttons-if-0-button-is-reported.patch
and it can be found in the queue-4.4 subdirectory.

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

From: Aaron Ma <[email protected]>
Date: Fri, 19 Jan 2018 09:43:39 -0800
Subject: Input: trackpoint - force 3 buttons if 0 button is reported

From: Aaron Ma <[email protected]>

commit f5d07b9e98022d50720e38aa936fc11c67868ece upstream.

Lenovo introduced trackpoint compatible sticks with minimum PS/2 commands. They supposed to reply with 0x02, 0x03, or 0x04 in response to the "Read Extended ID" command, so we would know not to try certain extended commands. Unfortunately even some trackpoints reporting the original IBM version (0x01 firmware 0x0e) now respond with incorrect data to the "Get Extended Buttons" command:

thinkpad_acpi: ThinkPad BIOS R0DET87W (1.87 ), EC unknown
thinkpad_acpi: Lenovo ThinkPad E470, model 20H1004SGE

psmouse serio2: trackpoint: IBM TrackPoint firmware: 0x0e, buttons: 0/0

Since there are no trackpoints without buttons, let's assume the trackpoint has 3 buttons when we get 0 response to the extended buttons query.

---
 drivers/input/mouse/trackpoint.c |    3 +++
 1 file changed, 3 insertions(+)

@@ -383,6 +383,9 @@ int trackpoint_detect(struct psmouse *ps
 	if (trackpoint_read(&psmouse->ps2dev, TP_EXT_BTN, &button_info)) {
 		psmouse_warn(psmouse, "failed to get extended button data, assuming 3 buttons\n");
 		button_info = 0x33;
+	} else if (!button_info) {
+		psmouse_warn(psmouse, "got 0 in extended button data, assuming 3 buttons\n");
+		button_info = 0x33;
 	}
 
 	psmouse->private = kzalloc(sizeof(struct trackpoint_data), GFP_KERNEL);

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

queue-4.4/input-trackpoint-force-3-buttons-if-0-button-is-reported.patch