elantech touchpad issues

["Richard Schütz" <r.schtz@t-online.de>]

I noticed that the elantech driver reports totally wrong axis range 
values to the xf86-input-synaptics driver for the touchpad in my Samsung 
N145 Plus netbook.

kernel output:
elantech: assuming hardware version 2, firmware version 4.2.22
elantech: Synaptics capabilities query result 0x09, 0x14, 0x0b.

As it's detected as hardware version 2 the hardcoded ranges from 
elantech.h are used:
[    16.863] (--) ETPS/2 Elantech Touchpad: x-axis range 8 - 1144
[    16.863] (--) ETPS/2 Elantech Touchpad: y-axis range 8 - 760

But with synclient's monitor mode I discovered that the correct values 
for my touchpad seem to be:
min x: 0
max x: 819
min y: 355
max y: 760
(without ETP_EDGE_FUZZ_V2)

This results in unusuable edge areas by default.

When using more then one finger on the touchpad also sometimes this 
strange thing happens and the cursor jumps:
    time     x    y   z f  w  l r u d m     multi  gl gm gr gdx gdy
155.600  1020 -268  31 2  0  0 0 0 0 0  00000000
155.610  1020 -268   0 0  0  0 0 0 0 0  00000000
(the second line is optional)

I guess this would have no effect (like jumping cursor) with correct 
ranges. Can't they be queried from hardware? I have no clue if these 
ranges I figured out are valid for my netbook only or if there was a 
general change in newer firmware versions. Unfortunately, I own no other 
hardware for figuring this out. I could patch the driver for my personal 
need, but I think this should by handled somehow in the driver 
automatically. If that would not work adequate I would suggest to 
introduce driver parameters to pass the ranges at runtime without the 
need for recompiling.

-- 
Regards,
Richard Schütz
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