Re: [PATCH v9 1/8] drivers:input:tsc2007: add new common binding names, pre-calibration, flipping and rotation

[Petr Cvek]

Hi,

Dne 20.2.2017 v 22:50 Dmitry Torokhov napsal(a):
> On Mon, Feb 20, 2017 at 1:27 PM, H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> wrote:
>>
>>> Am 20.02.2017 um 22:08 schrieb Pali RohÃr <pali.rohar@xxxxxxxxx>:
>>>
>>> On Monday 20 February 2017 20:42:15 Pali RohÃr 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).

best regards,
Petr