On Tuesday 06 February 2018 10:29:47 Peter Hutterer wrote: > On Mon, Feb 05, 2018 at 02:49:55PM -0800, Dmitry Torokhov wrote: > > On Sun, Feb 04, 2018 at 04:08:39PM +0100, Pali Rohár wrote: > > > Hi! Now playing again with trackpoint connected to ALPS rushmore > > > touchpad and I'm seeking a nice feature. Via ALPS PS/2 protocol it > > > reports pressure of trackpoint. Parser for it is already implemented in > > > alps.c and value is assigned to variable "z". When I just move > > > trackpoint z is zero, when I push trackpoint while moving, then z is > > > number higher, maximally 32. Variable "z" is set, but unused. > > > > > > Do we have some input interface which can be used to report this > > > pressure of trackpoint to userspace? I can use this feature e.g. as > > > additional button... > > > > We could either do the conversion in kernel and emit BTN_LEFT, or > > report ABS_PRESSURE and see if userspace will be able to handle > > REL_X/REL_Y/ABS_PRESSURE device. > > > > Adding Peter. > > judging by trackpoint history, I'd leave the pressure->click conversion to > userspace because every trackpoint may need a different threshold setting. > "easier" to have this in userspace with dmi matches etc. plus, converting to > BTN_LEFT in the kernel means we cannot use it as a separate interaction > anymore. Also BTN_LEFT is already reported when left button under trackpoint is pressed. Therefore it would not be possible to distinguish between trackpoint "press" and real left button press. > That aside, I think exporting ABS_PRESSURE is fine, that's what it's there > for. Nothing will use it for now though, tbh not sure yet how that would be > exported from libinput. but worth filing a bug for, please assign it to me. Ok, so ABS_PRESSURE? Also then question is, how to report minimal and maximal (possible) value? If we are going to "standardize" API for it, we should also define min/max values, so userspace would be able to normalize this pressure event. I can imagine that some devices can report 8bit value, but ALPS rushmore reports only 5bit value. -- Pali Rohár pali.rohar@xxxxxxxxx
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