Hello! I'm an owner of a Thinkpad T440p, and was always unhappy with the buttonless trackpad. I was ecstatic when I learned that trackpads from the 50 series laptops, with buttons, are compatible with 40 series laptops. I have since performed this mod, and all of the hardware seems to be working. The only problem I've been having is a software one. It seems that the trackpad and trackpoint are usually arranged such that the trackpoint is "behind" the trackpad and all communication with the trackpoint goes through the trackpad. This allows the trackpad to provide an abstraction of the trackpoint for OSes that don't explicitly support it. With my old trackpad, which was a Synaptics device, Linux would detect the trackpoint as its own device with the TPPS/2 protocol. It seems that it was able to do this because the Synaptics driver has support for a "pass-through port" which allows the OS to send commands directly to the trackpoint. However, the new trackpad that I received is an ALPS v7 device. I see some references to passthrough support in drivers/input/mouse/alps.c, but it doesn't appear to be used in the same way as it is in the Synaptics driver and doesn't seem to be supported at all for v7 devices. Therefore, instead of showing up as its own special device, the trackpoint shows up as a "DualPoint Stick". In general this is fine, because the trackpoint works. However, the dedicated trackpoint driver allows you to modify a few trackpoint-specific hardware settings, most notably the sensitivity. This was much more of an issue before this: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=088df2ccef75754cc16a6ba31829d23bcb2b68ed commit, but I still think it would be nice to be able to control my hardware as much as possible. Interestingly, I've been able to find very little discussion of this limitation of the ALPS driver. Here are the few links that I've been able to find: https://bugzilla.kernel.org/show_bug.cgi?id=8864 (comment 24 seems especially relevant) https://bugzilla.redhat.com/show_bug.cgi?id=483224 http://www.spinics.net/lists/xorg/msg49549.html http://thinkpad-forum.de/threads/185025-T*50-Clickpad-in-T*40-Trackpoint-Konfiguration (German) Since the trackpad that I received is from some Thinkpad model (I don't know which one though), there presumably should be other 50 series Thinkpad users who are affected by this same issue. It could just be that the number of people with the right device who use Linux and want to adjust the hardware sensitivity and care enough to post about it online is essentially zero, but I've had a hard time convincing myself of this. Comment 24 in the first link states that ALPS has been unwilling to share the secret to the passthrough port for their hardware. However, this comment is 8 years old, so I'm hoping things have changed. The second and third links seem to be describing approximately the same problem, with one difference being that disabling the trackpad in the BIOS does not cause the trackpoint driver to be used for me - it only causes the trackpad device to stop emitting events. Perhaps this is because the buttons are now part of the trackpad device, or maybe it's just because this is a non-standard mod. The fourth link seems to be describing the exact problem that I'm having, however my ability to read German is only as good as Google Translate ability to translate it. If there's anything that I can do to help get this implemented, please let me know. I'd even be willing to try and figure out how the Windows driver does this, if that becomes necessary. Also: I am aware that sensitivity/speed/acceleration/whatever can be adjusted somewhat through libinput settings. That is not what I'm asking about, so please don't suggest it. :) Thanks! Ari -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
