On Fri, Mar 18, 2022 at 03:06:55PM +0100, Benjamin Tissoires wrote: > On Fri, Mar 18, 2022 at 2:11 PM Takashi Iwai <tiwai@xxxxxxx> wrote: > > > > Hi, > > > > > > > > we received a bug report about the regression of the touchpad on Dell > > > > 7750 laptop, the right touchpad button is disabled on recent kernels: > > > > https://bugzilla.suse.com/show_bug.cgi?id=1197243 > > > > > > > > Note that it's a physical button, not a virtual clickpad button. > > > > > > > > The regression seems introduced by the upstream commit > > > > 37ef4c19b4c659926ce65a7ac709ceaefb211c40 ("Input: clear > > > > BTN_RIGHT/MIDDLE on buttonpads") that was backported to stable 5.16.x > > > > kernel. > > > > > > > > The device is managed by hid-multitouch driver, and the further > > > > investigation revealed that it's rather an incorrectly recognized > > > > buttonpad property; namely, ID_DG_BUTTONTYPE reports it being 0 = > > > > clickable touchpad although it's not. I built a test kernel to ignore > > > > this check and it was confirmed to make the right button working again > > > > by the reporter. > > Yep, I came to the same conclusion this morning with the reporter of > the libinput bug José was mentioning. > > > > > > > > > Is this check really correct in general? Or do we need some > > > > device-specific quirk? > > The device firmware is clearly wrong here. It's the first time I see > this failing like that and I hope this is just an isolated case. > The device advertises itself as a buttonpad, when it's not. > > However, the fact that it passed MS certification (even if I doubt > Microsoft ever got that touchpad in their own hands) leads me to > believe that the certification doesn't enforce that setting too much, > and that we might see more devices coming in with that same bug. > > To sum up, I am not happy that this commit introduced a regression > that we can not work around in userspace: given that BTN_RIGHT gets > removed from the device, all of the values are filtered out and > userspace can not resolve that situation by itself. > > I wish I had a better way of fixing this than having to quirk the device. > > > > > > > A couple of days ago another user with the same laptop (Dell Precision > > > 7550 or 7750) emailed me to report the issue and I sent him a patch for > > > testing. > > > > > > I he confirms that the patch works, I'll send it to the mailing list. > > > > > > I believe that your analysis of the regression is correct and I think > > > that we'd need to add a quirk for the device. > > > > > > In case you want to have a look to the patch, I added it to this > > > libinput [1] report. > > > > Great, I'll try to build and ask the reporter to test with the patch. > > > > As noticed on the libinput bug, I think the patch is wrong (not by a lot). > We should base the class on MT_CLS_WIN8, not MT_CLS_DEFAULT. Thanks for providing the right class Benjamin, I updated the patch: https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/726#note_1303724 Jose
