I installed manjaro hoping Acer Aspeire’s touchpad will work, but it wasn’t.
Before it, I tried it on debian, but there is the same.
In BIOS, the I2C setting is set and there is PS/2 one. I tried both ones, but the touchpad doesn’t work.
I found and installed i2c-tools package - not work.
Asking Google about “acer aspire a3 touchpad linux” I found two essentially different ways people have solved this.
One is through a Bios setting.
The other is by adding some parameters to the boot loader command line.
All the links are to the Mint forum - but Linux is Linux is Linux
and what applies there, does apply everywhere.
So:
see whether one of these ways can help you as well.
first link
second link
third link
As mentioned in at least one of these threads:
info on your hardware (inxi -zv8) is the minimum information needed for anyone to attempt to help
ps:
I don’t know why I searched for “aspire a3” instead of what you actually wrote 
I just noticed the error
unconscious bias or a simple typo
… perhaps it helps anyway
Thanks very much! I going to mark the issue as a solution and think about suggested acts, because I am afraid of breaking something (I have a lot of experience with it 
).
so:
you don’t know it is a solution, but you still mark it as such?
because you didn’t dare or try to test and confirm or deny?
potentially leading others astray?
Can’t accept that.
Will report it - to remove the “solution” mark.
Because it isn’t a solution.
Not until you confirm it.
It’s not obvious when new, but when in doubt in providing information for help, try to provide the output of inxi -v8z
The touchpad is configured differently in X11 and Wayland, sometimes your desktop environment is a major factor too. The output of that command would have all that information in there, plus so much more.
I ran into one laptop, just 2 months ago,where it was impossible for me to get it working in Wayland after 100 hours of troubleshooting, and I had to go back to X11.
as far as I’m concerned: it’s all in those linked threads
but
he didn’t even try
and I had the solution mark removed by powers greater than him 
I predict this thread may become a zombie.
I apologise to everyone for wasting your time.
The touchpad is working - it’s just that I inadvertently didn’t see that the touchpad was locked (literally with a key). That’s and apparently the touchpad works out of the box in manjaro and debian.
I’m really sorry.
Yay! 
easy peasy
Thank’s for the feedback!