About Beaglebone Black device tree

[Vijay Kumar Banerjee]

On Sun, Feb 2, 2020 at 9:49 PM Christian Mauderer <list at c-mauderer.de>
wrote:

>
> On 31/01/2020 17:43, Vijay Kumar Banerjee wrote:
> >
> >
> > On Fri, Jan 31, 2020 at 9:59 PM Christian Mauderer <list at c-mauderer.de
> > <mailto: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.
>
> Thats not good. But the correct way would be to find out what's wrong
> and fix it. Did they add a fix in a future FreeBSD version?
>
> Most likely the overlay isn't working as expected. I'll have to have a
detailed
look to figure out what's going on there.

> >
> >     >
> >     >>
> >     >> 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/
>
> Following the FreeBSD tree is a good point. But would they be visible
> there? Beneath that: We currently don't have support for building the
> overlays. Do you have an idea how that could look like?
>
> keeping it visible will be a problem. For building the overlay, we can use
dtc
and add a script to build the overlay. I see that rsb has a build package
for
devel/dtc.bset as well.

> Best regards
>
> Christian
>
> >
> >     > Best regards
> >     >
> >     > Christian
> >     >
> >     >>
> >     >> Best regards,
> >     >> Vijay>
> >     >> _______________________________________________
> >     >> devel mailing list
> >     >> devel at rtems.org <mailto:devel at rtems.org>
> >     >> http://lists.rtems.org/mailman/listinfo/devel
> >     >>
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.rtems.org/pipermail/devel/attachments/20200202/c8febfa9/attachment.html>