I had installed the touchscreen on the gpio of my pi 0w and did worked like a charm.
Then I decided to install Xserver, lightdm :
sudo apt install raspberrypi-ui-mods
After what the screen is grey and had just a cursor at the upper left corner and that's it !
I tried several changes in lightm et X11 config files without results, and then atarted to change de /boot/config.txt as follow :
hdmi_group=2 hdmi_mode=1 hdmi_mode=87 hdmi_cvt=480 320 60 6 0 0 0 dtparam=spi=on dtoverlay=ads7846
Here is the log for lightdm :
juin 01 11:31:36 raspi01 lightdm: pam_unix(lightdm-greeter:session): session opened for user lightdm by (uid=0)
I still have a correct screen out of the HDMI port, with resolution 480 x 320.
So what can I do next ? Thanks.