> dtoverlay=spi1-1cs,cs0_pin=18 However this line is not be necessary. It sets up spidev for spi1. https://github.com/raspberrypi/linux/blob/rpi-5.4.y/arch/arm/boot/dts/overlays/spi1-1cs-overlay.dts#L34 The next overlay removes spidev again. https://github.com/raspberrypi/linux/blob/rpi-5.4.y/arch/arm/boot/dts/overlays/mcp251xfd-overlay.dts#L35 -- Patrick
