Re: [PATCH v1 0/5] Convert recently merged T30 boards to use DM PMIC

[Thierry Reding <treding@nvidia.com>]

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On Mon, Nov 06, 2023 at 04:04:07PM -0500, Tom Rini wrote:
> On Mon, Nov 06, 2023 at 02:11:16PM +0000, Peter Robinson wrote:
> > On Mon, Nov 6, 2023 at 1:28 PM Svyatoslav Ryhel <clamor95@gmail.com> wrote:
> > >
> > > пн, 6 лист. 2023 р. о 15:13 Peter Robinson <pbrobinson@gmail.com> пише:
> > > >
> > > > On Mon, Nov 6, 2023 at 11:58 AM Svyatoslav Ryhel <clamor95@gmail.com> wrote:
> > > > >
> > > > > пн, 6 лист. 2023 р. о 13:46 Peter Robinson <pbrobinson@gmail.com> пише:
> > > > > >
> > > > > > Hi Svyatoslav,
> > > > > >
> > > > > > > Since the proposed PMIC patches have been accepted, I see the need
> > > > > > > to convert boards which I maintain to use DM drivers instead of board hacks.
> > > > > > >
> > > > > > > Svyatoslav Ryhel (5):
> > > > > > >   board: lg-x3: convert LG Optimus 4X and Vu to use DM PMIC
> > > > > > >   board: endeavoru: convert HTC One X to use DM PMIC
> > > > > >
> > > > > > Is there a reason why the two above devices don't appear to have their
> > > > > > .dts files in the upstream kernel?
> > > > > >
> > > > >
> > > > > Yes, there is a reason. Linux maintainers treat submitters as
> > > > > existential enemies or as dirt at least. I was trying to work with
> > > > > linux but I have no desire to spend any time to upstream endeavoru or
> > > > > lg_x3.
> > > >
> > > > The usual policy for acceptance into U-Boot is to have upstream review
> > > > in the kernel first.
> > > >
> > >
> > > May you point to a policy which clearly and explicitly states this as
> > > a mandatory condition?
> > 
> > There have been a number of devices rejected in the past until their
> > DT are upstream but I'll leave Tom, who I've explicitly added on cc:,
> > to clarify the exact policy.
> 
> Well, here is where it's tricky. I brought this up for one of the
> Broadcom MIPS platforms a week or two back, and Linus Walleij's point
> (and I'm paraphrasing) is there's not really an upstream for it to go.
> 
> What we cannot have is device tree bindings[1] that aren't upstream or
> worse yet conflict with the official bindings.
> 
> So the general way to resolve that is have device tree file be drop-in
> from the linux kernel, and what additions we must have be done via
> -u-boot.dtsi files. And in turn, some SoCs are better about keeping in
> sync with the kernel than other SoCs are.
> 
> Now, upstream being actively hostile to dts files, especially for older
> platforms? That's unfortunate. So long as we aren't violating the rules
> about bindings, the intention is that we don't have device trees that
> are either (a) massively out of sync with the kernel[2] or (b) kept
> intentionally mismatched from the kernel.
> 
> -- 
> Tom
> 
> [1]: There are both examples like binman that Simon is working on at
> least but this is more exception than intentional rule.
> [2]: Per our other conversions, I know the tegra ones are in this
> unfortunate state in general

On the Tegra side we've been fairly lax about the device trees in
U-Boot, I suppose. The assumption had always been that U-Boot would load
an external DTB and pass it to the kernel on boot, so keeping them both
in sync was never a high priority.

U-Boot does only a very tiny amount of what Linux does, so dropping in
the kernel DTB always seemed a bit overkill.

In either case, if this is problematic, it's something that I could take
a look at. Again, it's expected that the device trees are different, for
historical reasons, but I'd be surprised if they actually conflict with
one another. U-Boot's DTB was always supposed to be a subset of the
Linux DTB.

Thierry

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