7i73 LCD shows rubisch

Can not reach my machine tonight anymore, but I use master ca 1.5 weeks ago.
The 7i73 firmware? No idea. Same for 7i76e, but it worked flawless when i tested in the beginning.

Picture makes no sense. Better i describe.
For test i just use ABC, in the first position of first line. It i writen there.
But these three letters are immediately positioned additionally everywhere on the screen. I guess it is at least 10 times per second.
I know lcd from my earlier AVR programming times. Could have a similar problem when errors in position commands.

HI My wife will kill me
could not resist and honor your effort... THX

I have 7i76e so had to modify your code to:

loadrt hostmot2
loadrt hm2_eth board_ip="192.168.1.121" config="sserial_port_0=21xxxx"
loadrt lcd fmt_strings="LinuxCNC - Tool %2i\n%b* X Pos = %11.4f%b* Y Pos = %11.4f%b* Z Pos = %10.3f|Long Number\n%015.2f\n"
loadrt threads
loadrt siggen
addf hm2_7i76e.0.read thread1
addf hm2_7i76e.0.write thread1
addf lcd thread1
addf siggen.0.update thread1
net chars lcd.00.out hm2_7i76e.0.7i73.0.1.display
start
setp lcd.00.contrast 0.7
net stuff lcd.00.page.00.arg.02 siggen.0.sine
net stuff1 lcd.00.page.00.arg.04 siggen.0.cosine
net stuff2 lcd.00.page.00.arg.06 siggen.0.triangle
setp lcd.00.page.00.arg.03 1
setp siggen.0.amplitude 1000
setp siggen.0.frequency 0.000005

Result is the same
Can see your text on the screen, but it is overwritten very fast, much more then the guessed 10 times per second
on various positions. The basic image is more or less "reconstructed" on the same place.
Mike

P.S.
I have to move in my bed now, when I intend to survive...
Big THX
Mike

@Mr.kuzminsky

The 2018 January 14 update went from 1:2.8.0~pre1.3405.ge10c52ea6 to 1:2.8.0~pre1.3520.g0a096c965, which is a pretty large jump that includes the commit Rene pointed out. So that's valuable debugging, thanks.

How do you solve this? is this pure looking to the code difference on git?
I like to look at difference also. Sometimes it's boring, but if it work's after compiling it can be great !
I like to learn more about linux.

@Andy,

I will try to look in the code difference on git between :
1:2.8.0~pre1.3405.ge10c52ea6 to 1:2.8.0~pre1.3520.g0a096c965

And then look carefully for changes in touchscreen. It can be a one letter mistake.

I was never good in programming c, but i would look for a slightly changed size in an array, or a loop counter that does not fit anymore. I'm only guessing that the "real" positioning commands come from the 7i73 firmware.
Mike