[popcornmix]

Thanks. I tried "device_tree_param=spi=on" first and it worked. I thought that there won't be needed any manual changes to config.txt now.
Not sure what improvements device tree support brings, but in terms of usablility this feels like a step backwards to me.

The issue is most people don't use spi/i2c/i2s/lirc but the modules were all enabled by default and they conflict (e.g. you can't use an i2s audio card without blacklisting lirc_rpi).
So we needed a scheme where you can opt in to these.

The longer term goal is to use the "HAT detection" pin, so external cards can identify themselves and the appropriate device tree overlay will be selected automatically.
The config.txt mechanism allows cards that don't support that to still be used.