Background
As the RevPi Core 1 has limited performance, in most scenarios it is no longer an option. Therefore, officially the latest released buster images are not focused on RevPi Core 1 and thus not be tested on it. However, to assist the user who still haves some reason to continue there work on it, we provide a workaround to make the Buster image to run on Core 1.
Reason
The known reason preventing Buster image runing on Core 1 is the usb driver. From RevPi Buster image of 05-2022, we started to use DWC2 instead of DWC-OTG as the usb driver, which can run better on CM 3 and CM 4S based devices. But the DWC2 is not fit for CM 1, so to run the Buster image on Core 1, the usb driver needs to go back to DWC-OTG.
Workaround
The usb driver is specified in device tree overlay on RevPi device, which includes the configurations in /boot/overlays/revpi-core.dtbo and /boot/config.txt. For Core 1, in revpi-core.dtbo, the usb driver has been chosen as DWC2. As the dtbo file is in binary format, it is not fit for further adaption. So the config.txt would be the right file to do the change. It is sufficient to add the specifying of DWC-OTG in /boot/config.txt by adding “dtoverlay=dwc-otg" after whole configuration block of "dtoverlay=revpi-core " . As the idea is to make an amend for the specifying of usb driver, so place it after the DT overlay of revpi-core is needed.
The Step-by-Step guide
flash the RevPi Core 1 with latest Buster image
do the factory reset as before
with command “
echo -e "\r\ndtoverlay=dwc-otg" | sudo tee -a /boot/config.txt" add configuration of dwc-otg to config.txtreboot the device