SPI automatic interface configuration inside of cpu.c/periph_init(();

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1

Dear RIOT developers,

I think it is not a good idea to initilialize the SPI interface automatically via the periph_init() function because it is not as static as mentioned.

In my application I have 2 SPI interfaces defined in the periph_conf.h file - but I wanted only to configure the second one of these interfaces.

I the older days everything went well, but when I pulled in the new sources I was wondering why now the spi_init() function was invoked 3 times....2 times automatically by the periph_init() function (initializing all defined interfaces) and one time by my own (initializing only the second interface).....and it took some time to find out what was going wrong.

For my opinion interface initialization should be under control of the application which interface is set up.

Best regards,

Neo

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Hi Neo,

the global/automatic SPI initialization might not be ideal, but the benefits are greater than the drawbacks. One of the major design issues this is solving is the handling of shared peripherals (as in SPI/I2C): when doing the initialization somewhere in the driver code, different driver will re-initialize the same peripheral, potentially with contradicting settings...

For your specific problem: if you only use one specific SPI and use pins configured to another SPI dev for other purposes, then the other SPI should not be configured, so you should use an application specific `periph_conf.h` file. This should fix your issues.

Cheers, Hauke