Yeah, as I was saying, I actually do remember how to do that, and successfully 
did. I still end up having to do the export and then other sysfs stuff to set 
the values.

Which, as I think about it, setting the values in the DTB is not so useful.* I 
do need to turn things on and off only under software control. But it'd be nice 
to get rid of the export step.

*There are a couple of GPIOs that turn regulators on and enable some of my 
audio circuitry. In theory, I can build the device tree including those, and 
then the audio APIs turn them on automatically when audio is enabled. But I've 
had limited success with getting that right.

> On Apr 3, 2016, at 17:26 , William Hermans <[email protected]> wrote:
> 
> Here Rick, maybe this will refresh you on the subject. 
> http://stackoverflow.com/questions/16872763/configuring-pins-mode-beaglebone 
> second answer I think talks about device tree files, while the first one 
> talks about some crazy script method . . .
> 
> But essentially, and I'm no expert here, and from the second answer . . .
> 
> pinctrl-single,pins = <
>                                     0x070 0x2f /* P9_11 30 INPUT MODE7 none */
>                                     0x074 0x2f /* P9_13 31 INPUT MODE7 none */
>                                     0x040 0x2f /* P9_15 48 INPUT MODE7 none */
>                                     0x15c 0x2f /* P9_17 05 INPUT MODE7 none */
>                             >;
> 
> This in it's self does a lot of explaining here. Check out the comments for 
> each pin, and mode. 
> 
> On Sun, Apr 3, 2016 at 5:18 PM, Rick Mann <[email protected]> wrote:
> 
> > On Apr 3, 2016, at 17:07 , William Hermans <[email protected]> wrote:
> >
> > Yes, it can be done. I thought you had all this down before ? You can 
> > configure what mode the pin is actually used for - The several different 
> > peripheral types per pin, or GPIO + pull up/down or neither, and pin 
> > direction.
> 
> Sorry, I haven't been able to touch this since last summer, and I don't 
> always remember what I figured out. I do recall that I can set up the pin, 
> but I've never figured out for sure how to set the output state.
> 
> Also, I've never succeeded in getting a full DTB working (one that sets up my 
> pins, ADC, PRU, and audio). I'm hoping enough progress has been made in the 
> kernels that I can finally get there. And I'm getting closer, just not quite 
> there yet.
> 
> --
> Rick Mann
> [email protected]
> 
> 
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