[PATCH 00/21] Qualcomm generic board support

[ff]

Le 7 déc. 2023 à 19:51, Rob Herring <robh+dt at kernel.org> a écrit :

On Thu, Dec 7, 2023 at 2:08 AM ff <ff at shokubai.tech> wrote:



Le 6 déc. 2023 à 21:42, Rob Herring <robh+dt at kernel.org> a écrit :

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?

What about leveraging SystemReady-IR compliant board maintainers and start with a core of motivated people ?

I think there are 2 ATM. Synquacer and i.MX8 variants.

Based on  https://www.arm.com/architecture/system-architectures/systemready-certification-program/ir
 roughly 30 boards.

Synquacer only
has a DT in u-boot, so not really anything to do there.
I'm pretty
sure the certified DTBs for i.MX8 don't match what's in u-boot or the
kernel tree. Hopefully, it's just a subset, but still, there's a gap.
I don't know that there is motivation there either.
Note that SystemReady currently only requires every node with
'compatible' have a schema. It does not yet require no schema
warnings. If we went with a 1 by 1 approach, I would push that
platforms have to be free of warnings.

How many years will that take?

Should all platforms following that organization be a goal?

You mean should all platforms be moved? Absolutely. I don't think we
want to solve the problem of having DTS files in 2 places by creating
a 3rd place.
Actually, if we limit he DTS in the third place for SystemReady-IR, there should be no DTB in the Linux distribution. It would be the equivalent as ACPI boards . So is it still an issue ? A reference to the the third repo may be hinted in a text file.

I don't really think 1 by 1 is the right approach. I was just
enumerating how this could work. It's not that useful to say we need a
standalone repo without working thru the logistics of how exactly that
will work.

Rob