This is because these fragment names dont actually matter neither does the order or the number you could change fragment@1 to fragment@4 and you would get the same randomness. You will need to split 4xMCP2517FD.dts into MCP2517FD-can0.dts MCP2517FD-can1.dts MCP2517FD-can2.dts and MCP2517FD-can3.dts and define your /boot/config.txt in the order you need it. dtoverlay=mcp2515-can0-overlay,oscillator=16000000,interrupt=Xx dtoverlay=mcp2515-can1-overlay,oscillator=16000000,interrupt=Xx dtoverlay=mcp2515-can2-overlay,oscillator=16000000,interrupt=Xx dtoverlay=mcp2515-can3-overlay,oscillator=16000000,interrupt=Xx We ran though a similar issue on our dual can board. I am by no means a device tree expert but /boot/config.txt does get processed in order where as those DTS files get parsed by for_each_child_of_node() Which does not guarantee init order. I believe there are some tricks you can do but they aren't very clean or involve editing drivers/of/overlay.c and thats a total pain. Sorry If someone gets this two or three times I forgot to turn on plaintext only mode. On Tue, Sep 11, 2018 at 3:30 PM Hubert Denkmair <xor@xxxxxxx> wrote: > > Hi all, > > I'm currently building a open hardware Raspberry Pi HAT > with four MCP2517FD SPI CAN controllers: > https://github.com/Bytewerk/QuadCAN-FD/tree/v1 > > This seems to work with the device tree overlay from said > repository and Martin Sperls latest MCP25xxFD patches \o/ > > Now, I have one problem and I'm not sure how to address this. > I'm using a Raspberry Pi 3 Model B+ with current raspbian. > > Maybe 90% of all boots, I get the following in dmesg: > --- > [ 3.877118] mcp25xxfd: loading out-of-tree module taints kernel. > [ 3.890743] mcp25xxfd spi0.0 can0: MCP2517 successfully initialized. > [ 3.901189] mcp25xxfd spi0.1 can1: MCP2517 successfully initialized. > [ 3.910035] mcp25xxfd spi1.1 can2: MCP2517 successfully initialized. > [ 3.920515] mcp25xxfd spi1.0 can3: MCP2517 successfully initialized. > --- > > But sometimes, the SPIs seem to get enumerated in different order: > --- > [ 3.720432] mcp25xxfd: loading out-of-tree module taints kernel. > [ 3.733176] mcp25xxfd spi1.1 can0: MCP2517 successfully initialized. > [ 3.741914] mcp25xxfd spi1.0 can1: MCP2517 successfully initialized. > [ 3.750370] mcp25xxfd spi0.0 can2: MCP2517 successfully initialized. > [ 3.758741] mcp25xxfd spi0.1 can3: MCP2517 successfully initialized. > --- > > Also, I sometimes see the kernel taint message twice or even more. > I expect this to be a concurrency problem with one CPI core enumerating > one SPI bus, and another core enumerating the other? > > What's the best(tm) way to ensure consistent device naming in such a setup? > Is there anything that could be done in device tree > (so that I wouldn't have to touch the linux image itself)? > > Thanks, > > Hubert
