[PATCH 00/21] Qualcomm generic board support

[Sumit Garg]

On Thu, 7 Dec 2023 at 02:12, Rob Herring <robh+dt at kernel.org> wrote:
>
> On Tue, Dec 5, 2023 at 11:05 PM Sumit Garg <sumit.garg at linaro.org> wrote:
> >
> > On Tue, 5 Dec 2023 at 15:39, Krzysztof Kozlowski
> > <krzysztof.kozlowski at linaro.org> wrote:
> > >
> > > On 05/12/2023 10:45, Sumit Garg wrote:
> > > > + U-boot custodians list
> > > >
> > > > On Tue, 5 Dec 2023 at 12:58, Krzysztof Kozlowski
> > > > <krzysztof.kozlowski at linaro.org> wrote:
> > > >>
> > > >> On 05/12/2023 08:13, Sumit Garg wrote:
> > > >>>>> @DT bindings maintainers,
> > > >>>>>
> > > >>>>> Given the ease of maintenance of DT bindings within Linux kernel
> > > >>>>> source tree, I don't have a specific objection there. But can we ease
> > > >>>>> DTS testing for firmware/bootloader projects by providing a versioned
> > > >>>>> release package for DT bindings? Or if someone else has a better idea
> > > >>>>> here please feel free to chime in.
> > > >>>>
> > > >>>> This doesn't work for you?:
> > > >>>>
> > > >>>> https://git.kernel.org/pub/scm/linux/kernel/git/devicetree/devicetree-rebasing.git/
> > > >>>
> > > >>> Thanks, this is certainly a good step which I wasn't aware of. Further
> > > >>> simplification can be done to decouple devicetree source files from DT
> > > >>> bindings.
> > > >>
> > > >> Why?
> > > >
> > > > I suppose you are already aware that Linux DTS files are a subset of
> > > > what could be supported by devicetree schemas. There can be
> > > > firmware/bootloader specific properties (one example being [1]) which
> > > > Linux kernel can simply ignore. Will you be willing to add all of
> > > > those DT properties to Linux DTS files and maintain them?
> > >
> > > We already added them and we already maintain them. DTS describes the
> > > hardware, not the OS-subset of the hardware.
> >
> > Let look at some numbers if your statement is justified or not for the
> > example I gave:
> >
> > u-boot$ git grep -nr bootph-* arch/arm* | wc -l
> > 4079
> >
> > linux$ git grep -nr bootph-* arch/arm* | wc -l
> > 267
>
> I have no control over whether anyone has submitted the other 3812 instances.
>
> > It looks like there is always going to be a catch up game regarding DT
> > properties which either Linux kernel or u-boot or any other
> > firmware/bootloader project don't care about.
>
> As long as dts files in u-boot are manually sync'ed, yes. That is the
> problem and it doesn't matter if we have a standalone repository or
> not.
>
> If you want to move in that direction, start automating what u-boot
> imports. You need to do that for bindings if you want to run
> validation, so why not dts files too?
>
> > > > However, DT bindings are something which should be common, the
> > > > hardware description of a device should be universal. IMO, splitting
> > >
> > > Both DT bindings and DTS should be common. I don't see the difference.
> >
> > If we really care about DTS to be common then the contribution model
> > has to change where there is a single repo hosting DT bindings and
> > DTS. All other projects whether it is Linux kernel or u-boot or any
> > other OS/firmware/bootloader are just consuming DTS files from that
> > single repo.
>
> Really, only the kernel and u-boot matter. No, I don't mean I don't
> care about other projects, but those are the 2 with the widest h/w
> support by far and which have a major effort to sync copies of dts
> files in both projects. The rest are just noise in terms of this
> problem.
>
> > I suppose this is something that Linux DT maintainers
> > have objected to in the past for ease of maintenance. I am not sure if
> > you folks are willing to change that stance.
>
> The issue is no one steps up to help maintain such a repository while
> there is lots of review and maintainer work on what goes into the
> kernel tree. I'm happy to direct my binding review attention to
> wherever the majority of the bindings go. But the work on the DTS side
> is mostly SoC tree maintainers and sub-maintainers.
>
> Assume for a minute we have this standalone repo. What happens next?
> We start with an empty repo and then merge and move platforms 1 by 1?
> How many years will that take? What do we do with platforms no one is
> interested in moving? Or do we start with devicetree-rebasing instead
> (That was the plan at one time) and sync u-boot back to that?

Thanks Rob for sharing further insights. So I have given this approach
a try here [1]. Lets see how it can serve u-boot community needs and
thereby bring DT bindings compliance in u-boot.

U-boot community, maintainers, custodians,

Feel free to play out with this DT bindings compliance idea here [1]
and let us know if this approach helps to reduce DT maintainence
burden alongside increasing compliance.

[1] https://github.com/u-boot/u-boot/pull/451

-Sumit

>
> All the work needed to get u-boot and kernel dts files in sync has
> virtually no dependency on a standalone repo. If the dts files aren't
> already kept in sync, someone has to figure the differences and
> eliminate them. Maybe some platforms are in good shape, but it is
> still a manual process. Fix that part, because a standalone repo does
> nothing for you until you do.
>
> > > > DT bindings alone would ease the compliance process for u-boot drivers
> > > > in quite similar manner to Linux drivers.
>
> There's no compliance of drivers really beyond checking if compatible
> strings used by drivers have a schema.
>
> Why is extracting the bindings out a problem? SystemReady has no issue
> doing just that for its compliance test.
>
> Rob