Hello, Distro: https://raspi.debian.net/ (sid) Hardware: Raspberry Pi Zero W Kernel version: 5.9.11 (linux-image-5.9.0-4-rpi) To access a device connected to my pi, I need the spi0 bus, and would like to not be doing GPIO bit-banging when there are perfectly good spi modules capable of using the SPI alternative mode of these pins. spi0 is declared in the vanilla devicetree for this device: arch/arm/boot/dts/bcm2835-rpi-zero-w.dts ends up including arch/arm/boot/dts/bcm283x.dtsi which contains: spi: spi@7e204000 { compatible = "brcm,bcm2835-spi"; reg = <0x7e204000 0x200>; interrupts = <2 22>; clocks = <&clocks BCM2835_CLOCK_VPU>; #address-cells = <1>; #size-cells = <0>; status = "disabled"; }; To my new-to-devicetree eye, this looks like this is intended to be overridden, at least with a status = "okay"; property (although a bit more is needed). As I believe is the correct way, I wrote a devicetree overlay doing this and a bit more in order to enable this bus and one of its device (the one matching the chip-select monitored by the board I connected). To confirm that I had no typo in my symbol names I ran fdtoverlay with the packaged device tree binary, plus my overlay, but could not get it to work, until I took a closer look at the packaged device tree and realised it lacks a __symbols__ section. So I pulled the source, added "-@" to the cmd_dtc rule in scripts/Makefile.lib, built the dtb, tested fdtoverlay against it and voila, it worked. I could then reboot with this devicetree, load my overlay and use spi0 with no further change. So now I wonder why this option is not enabled while there are these sections which seem to not be usable without an overlay ? And further, why it does not seem to be possible to enable with a kernel config option ? I must be missing something obvious, but I'm still failing to see it. Regards, -- Vincent Pelletier
