linux-kernel - Re: [PATCH] HID: lenovo: Restrict detection of patched firmware only to USB cptkbd

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Date: Fri, 22 Dec 2023 16:32:07 +0100
From: "Uli v. d. Ohe" <u-v@...lbox.org>
To: jkosina@...e.com
Cc: benjamin.tissoires@...hat.com, iam@...dikss.org.ru, jekhor@...il.com,
 linux-input@...r.kernel.org, linux-kernel@...r.kernel.org, me@...oinitsky.org
Subject: Re: [PATCH] HID: lenovo: Restrict detection of patched firmware only
 to USB cptkbd

I get buggy middle button scrolling behavior on my USB Compact Keyboard 
(i.e., "1st gen") with original, unmodified firmware and the patch (of 
Sep. 23).

Sometimes the keyboard sends REL_X events while the middle button is 
pressed. Thus the old "workaround" is disabled and middle button 
scrolling henceforth exhibits the known buggy behavior.

Explicitly, I can confirm that the following values occur, leading to 
erroneous disabling of the workaround:

cptkbd_data->middlebutton_state == 1
usage->type == 2 [i.e., EV_REL]
usage->code == 0 [i.e., REL_X]

The keyboard is identified by lsusb as:
ID 17ef:6047 Lenovo ThinkPad Compact Keyboard with TrackPoint

This was tested with kernel 6.1.67 which contains the backported patch 
(commit 6e2076cad8873cc2a9f96e4becab35425c3656dc).

I didn't test the latest patch of Dec. 12. However, I don't expect it to 
fix my issue as the only added condition
hdev->product == USB_DEVICE_ID_LENOVO_CUSBKBD
should be satisfied, which I understand is also the intention. 
(USB_DEVICE_ID_LENOVO_CUSBKBD == 0x6047, which is the device ID of my 
keyboard as reported by lsusb.)

Best regards,
Uli