Hi William!

Am Dienstag, 19. Juli 2016 19:54:02 UTC+2 schrieb William Hermans:
>
> SO, after talking with Robert and finding that all these kernel modules 
> that get loaded from cape_universal=enable. I wonder how this impacts other 
> capes such as the Logic supply RS232 / CAN cape that automatically loads 
> it's own device tree  overlay.
>
> Could capes such as this be loaded first, and then still have universal-io 
> capabilities ? 
>

You can replace cape_universal by the libpruio universal overlay. That 
doesn't enable drivers/subsystems (= saves power and resources 
consumptions), but has the same pinmuxing capability. It's even more safe, 
since it seems that cape_universal can damage your CPU by a sequence like

config-pin P9_42 gpio high
config-pin P9_92 gpio low

(I didn't test it, but if you do so, please report.)

Regarding other capes, libpruio ships with a tool to adapt the universal 
device tree overlay. It can generate overlays that do not claim a specified 
set of pins. Instead of fiddling with device tree entries, you just list 
the pins you want to get freed and let the tool deal with the low-level 
stuff. Such an overlay can get loaded before or after any other cape 
overlay.

In order to replace the config_pin tool, you can write small programs 
(compiled against libpruio), which do the pinmuxing and enable the 
subsystems in use (only that ones).

BR

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