It's not a jumping through the hoops it's a matter of fact. If I am using the DSI1 connector every display I have (from 2015 up to 2024) everything is working as expected.The firmware won't be caring about DSI displays. The original 7" 800x480 display is supported by the firmware, but we don't recommend jumping through the hoops to enable it.
If I am using the DSI0 connector (hence the change of the i2c bus from I2C0_SDA / I2C0_SCL to ID_SD / ID_SC) and modifiying the device-tree overlay adding the dsi0 flag, only a very recent display works as expected. All other displays does not work at all or they work strange (i.e. the screen is full of garbage or shifted).
By the way, after rebooting with some old displays, the i2c bus has no touch-screen devices found. Only a COLD-START will help in that case. A simple reboot command does not help to reset the device or I2C bus.
The device-tree has the current overlays:If you've added "dtoverlay=vc4-kms-dsi-7inch,dsi0" then it'll be enabled within the kernel, so check the kernel logs (dmesg) for errors.
i2c-0 should also be enabled by the overlay, so check with "sudo i2cdetect -y 0" as to what devices are responding - you may just get UU on 0x45 due to the kernel driver being registered, but there should also be address 0x38 for the touch controller.
dtparam=i2c_arm=on
display_auto_detect=0 <--- Initially set as '1' but it does not help at all
dtoverlay=vc4-kms-dsi-7inch,dsi0
and for using the PCF8563 RTC I need the extra i2c command to enable it as Real Time Clock
dtparam=i2c_vc=on
So actually the only display is working fine is the latest bought LCD RPI display 7 inches originally sold by Raspberry Pi Foundation.
All other displays are working only if they are running from DSI1.
As you can see, having the DSI1 / DSI0 issue here, I am forced to re-route the signals from DSI0 to DSI1 to the connector, meaning a new PCB has to be made.
Any help to use the old LCD Screens with the DSI1 connector???
Statistics: Posted by retrobitlab — Thu Dec 05, 2024 12:31 pm