On Mon, Feb 20, 2017 at 2:21 PM, Petr Cvek <petr.c...@tul.cz> wrote: > Hi, > > Dne 20.2.2017 v 22:50 Dmitry Torokhov napsal(a): >> On Mon, Feb 20, 2017 at 1:27 PM, H. Nikolaus Schaller <h...@goldelico.com> >> wrote: >>> >>>> Am 20.02.2017 um 22:08 schrieb Pali Rohár <pali.ro...@gmail.com>: >>>> >>>> On Monday 20 February 2017 20:42:15 Pali Rohár wrote: >>>>> Hi Nikolaus! >>>>> >>>>> On Monday 20 February 2017 17:50:04 H. Nikolaus Schaller wrote: >>>>>> Hi Dmitry, >>>>>> >>>>>>> Input driver may set resolution for given axis in units per mm >>>>>>> (or units per radian for rotational axis ABS_RX, ABS_RY, >>>>>>> ABS_RZ), and if you check the binding, you can use >>>>>>> "touchscreen-x-mm" and "touchscreen-y-mm" to specify the size of >>>>>>> entire touch surface and set resolution from it so that >>>>>>> userspace can calculate the proper scaling factor. >>>>>> >>>>>> How is this information exposed by the kernel to user-space? By >>>>>> scanning the DT file or tree? >>>>> >>>>> Set input_abs_set_res() from kernel. And in userspace call EVIOCGABS >>>>> ioctl() on input device. Look at struct input_absinfo, you should >>>>> have all needed information here. This is generic input interface, >>>>> no DT is needed. >>>> >>>> Looking at kernel code... via EVIOCSABS ioctl() you can even set >>>> resolution from userspace for specified input device. >>>> >>>> So this could be potentially used for calibrating input device from >>>> userspace? (In case DT data will not fully match current HW) >>>> >>>>> I hope that XServer is already using it for evdev devices... >>>>> >>>>> For whole implementation look at evtest program. That should be good >>>>> starting point for your userspace implementation. >>>>> >>>>> While I'm watching this discussion... in my opinion kernel should >>>>> just invert input axes (when needed) >>> >>> It is questionable why it should do that at all then. >> >> Because the task of the kernel is to provide unified view of the >> hardware. Axis swapping and inversion is needed to that "up" is always >> "up" and "right" is always "right". > > Actually my Xorg calibration 3x3 matrix is fine with both axis inverted (on > TSC2046).
Yes, you can make it work for your touchscreen as long as you know that it inverted somehow. How you gain this knowledge is the question. Thanks. -- Dmitry
