THS POST IS MOVED TO ISSUES
Today, I finaly had the time do load the latest image on a clean SD card. I also received the DSI cable to connect the RPI5 to the P7 version 1. Since I have this custom zynthian, I need webconf to configure it. That seemed to work great. Originally the config was a V5 with MIPI DSI 800x480 (inverted) and the wiring as Mini V2, but I changed that to what it is:
Raspberry Pi 5 Model B Rev 1.0
Audio: HifiBerry DAC+ ADC PRO
Display: Pi 7 Touchscreen Display 800x480
Wiring: MCP23017_ZynScreen
I2C: MCP23017@0x20, MCP23017@0x21
Profile: v4_stage
Except for the profile, that actually is a Custom.
After rebooting over and over again with or without (inverted) option and with the MIPI settings or the P7 settings, the screen stays upside down and also the previously made backup can load but has no effect.
When I insert the SD card I used for the RPI4 (which seems to work perfect) in the RPI5 everything seems to be fine again.
Also the screen is in the right position.
Raspberry Pi 5 Model B Rev 1.0
Audio: HifiBerry DAC+ ADC PRO
Display: Pi 7 Touchscreen Display 800x480
Wiring: MCP23017_ZynScreen
I2C: MCP23017@0x20, MCP23017@0x21
Profile: v4_stage