Hello,
I have been contending with the same issue with a generic 7" display. There is a configuration option in /boot/system.cfg that provides a variable ks_angle that is commented out. If you uncomment this line and provide the value “inverted”, as shown below
ks_angle = “inverted”
This is suppose to be honored by the system in setting up the X11 configuration, but for some reason Sovol’s implementation does not honor this variable!!!
A work-around that worked for me was changing my /etc/X11/xorg.conf.d/01-dbbian-defaults.conf in 2 places:
(1) As per biggy238’s recommendation to invert the screen, comment out the line by adding a # as shown below
#Option “Rotate” “UD” #这里是翻转的方向，“CW” (clockwise, 90 degrees), “UD” (upside down, 180 degrees) and “CCW” (counter clockwise, 270 degrees)
(2) To enable an inverted touch matrix, add a line below MatchIsTouchscreen “on” as follows
Option “TransformationMatrix” “-1 0 1 0 -1 1 0 0 1”
So for reference if anybody requires it, my /etc/X11/xorg.conf.d/01-dbbian-defaults.conf
is as follows:
************************************* BEGIN ******************************************
Section “Monitor”
Identifier “Monitor0”
Option “DPMS” “false”
EndSection
Section “ServerFlags”
Option “BlankTime” “0”
Option “StandbyTime” “0”
Option “SuspendTime” “0”
Option “OffTime” “0”
EndSection
Section “Device”
Identifier “default”
Driver “fbdev”
#Option “Rotate” “UD” #这里是翻转的方向，“CW” (clockwise, 90 degrees), “UD” (upside down, 180 degrees) and “CCW” (counter clockwise, 270 degrees)
EndSection
Section “InputClass”
Identifier “touchscreen catchall”
MatchIsTouchscreen “on”
Option “TransformationMatrix” “-1 0 1 0 -1 1 0 0 1”
Option “CalibrationMatrix” “-1 0 1 0 -1 1 0 0 1”
EndSection
************************************* END ******************************************
Hope this helps others who encounter the same problem 
