About Beaglebone Black device tree

[Vijay Kumar Banerjee]

On Fri, Jan 31, 2020 at 9:59 PM Christian Mauderer <list at c-mauderer.de>
wrote:

> On 31/01/2020 17:25, Christian Mauderer wrote:
> > On 31/01/2020 16:04, Vijay Kumar Banerjee wrote:
> >> Hi,
> >>
> >> While trying to run an rtems-littlevgl app on BBB, I found that the
> device
> >> tree generated from the freebsd source matching the freebsd-org
> >> HEAD commit doesn't work with the app and framebuffer device fails
> >> to open. This is most likely due to the changes in the freebsd dts
> >> sources because of which the overlay isn't working as expected.
> >
> > If I remember correctly, SD card doesn't work either with a FDT that is
> > too new.
> >
> >>
> >> I haven't had a detailed look at what's missing and the u-boot isn't
> >> reporting any error in applying the overlay either. I checked that the
> >> device tree built from freebsd tree matching the following commit
> >> works:
> >> 19a6ceb89dbacf74697d493e48c388767126d418
> >
> > At the moment that's the right one. But that can change if someone
> > updates libbsd again.
>
> And I have to correct myself: That is not the right one. The current
> libbsd HEAD should work with 6b0307a0a5184339393f555d5d424190d8a8277a.
>
> I meant to say that the framebuffer doesn't work with the current HEAD
(6b0307).
I checked with a previous commit, which is 19a6ce and found it working.
I should have been clear in the problem statement, sorry about that.

> >
> >>
> >> This brings up two questions:
> >> 1. Should we add the commit hash in the user manual so that the user can
> >> build
> >>     from source matching that commits instead of HEAD. This can be a
> >> problem
> >>     as other codes ported from freebsd might break if the device tree
> >> doesn't
> >>     match the HEAD commit of freebsd-org
> >
> > Adding a fixed commit id isn't really a good idea either. It is nearly
> > guaranteed that no one updates it if libbsd is updated. It would be
> > better to add instructions how to find out which commit should be used.
>
> The command would be:
>
>     git ls-files -s freebsd-org
>
> It works regardless whether the sub-module is initialized or not.
>
> >
> >>
> >> 2. How do we manage the device tree overlays required by RTEMS or
> libbsd?
> >>     I guess only BBB uses an overlay currently. Can we add a BSD
> license to
> >>     the overlay and add it somewhere in rtems or rtems-libbsd
> repository and
> >>     maintain it?
> >
> > I think you wrote the overlay so you can add any license you want. But
> > I'm really not sure where to put it. We currently don't have a location
> > for that. Do you have a good suggestion?
> >
>
How about rtemsbsd/sys/dts/arm/overlays ?
Following the freebsd tree freebsd/sys/dts/arm/overlays/

> > Best regards
> >
> > Christian
> >
> >>
> >> Best regards,
> >> Vijay>
> >> _______________________________________________
> >> devel mailing list
> >> devel at rtems.org
> >> http://lists.rtems.org/mailman/listinfo/devel
> >>
>
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