Hi Pali,

Am 20.02.2017 um 23:04 schrieb Pali Rohár [off-list ref]:

On Monday 20 February 2017 22:27:39 H. Nikolaus Schaller wrote:

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Am 20.02.2017 um 22:08 schrieb Pali Rohár [off-list ref]:

On Monday 20 February 2017 20:42:15 Pali Rohár wrote:

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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.

User-Space can also easily do it. Either the driver should provide
raw data only or if it does pre-processing (scaling by +/-1), why
exclude pre-scaling by other factors?

Via resolution property which is in that EVIOCSABS ioctl() you specify
value which represent unit per mm. So you cannot do full rescaling like
via affine transformation. Specially you cannot swap axes or invert it.

As such thing is not supported by current kernel <--> userspace API it
needs to be done in kernel.

Then, this what you asked for to be missing in the ABI and should be added
to clean upt the kernel drivers.

Moreover I see that this is already handled by kernel's of_touchscreen.c
code via DT properties: touchscreen-inverted-* touchscreen-swapped-x-y

Should be removed IMHO because user-space can do it equally well.
By setting the affine transform to negative values or use something
like ((0 -1) (1 0))

Or it should be processed as a generic value by the input core and should
not need to be implemented in every driver again and again.

If input core would handle these properties in a generic way, this patch
is no longer necessary (wrt flipping and rotation).

So please fix the input core so that it makes life of device driver developers
easier.

And... I'm not sure but I think that linux exports absolute input
devices with coordinates where point (0,0) is mapped as left upper
corner.

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and should not do any other
normalization or integer/floating-point
re-calibration/re-calculation. If it correctly exports minimum
value, maximum value and resolution then userspace can correctly
re-scale input events to units which userspace needs (e.g. mapping
into LCD screen pixels or whatever is needed).

BR and thanks,
Nikolaus