linux-kernel - Re: [PATCH v2 0/4] regulator: spacemit-p1: Fix voltage ranges and support board power tree

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Message-ID: <CAH1PCMZq++FYr_2WB=HvouXvnxcYGFk6tngqNUk3zTOM6xXLZQ@mail.gmail.com>
Date: Sun, 25 Jan 2026 12:18:23 +0800
From: Guodong Xu <guodong@...cstar.com>
To: Vivian Wang <wangruikang@...as.ac.cn>
Cc: Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, Yixun Lan <dlan@...too.org>, 
	Alex Elder <elder@...cstar.com>, Lee Jones <lee@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Troy Mitchell <troy.mitchell@...ux.spacemit.com>, Paul Walmsley <pjw@...nel.org>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Alexandre Ghiti <alex@...ti.fr>, linux-kernel@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev, 
	devicetree@...r.kernel.org
Subject: Re: [PATCH v2 0/4] regulator: spacemit-p1: Fix voltage ranges and
 support board power tree

On Sat, Jan 24, 2026 at 2:25 PM Vivian Wang <wangruikang@...as.ac.cn> wrote:
>
>
> On 1/24/26 08:20, Guodong Xu wrote:
> > [...]
> >
> > Note: Patch 3 introduces a bisect breakage by transitioning to
> > pin-specific supply names. Probe failures will occur on existing boards
> > until Patch 4 updates the corresponding DTS file.
>
> Ouch, that's not a bisect breakage, that's an *ABI breakage*. And AFAICT
> this is still not okay in 2026,
> see Documentation/devicetree/bindings/ABI.rst
>
> So the bindings would need to be changed to accept both the new and old way.

Ideally yes. However, considering this ABI change's actual effect, the two
K1 boards (BPI-F3 and Jupiter) in the kernel get their power settings
from boot firmware as well, and the types of peripherals enabled in the .dts
files are very limited, the probe failure of the pmic regulator doesn't
affect much. So, I think this breakage is acceptable.

>
> Driver-wise, at a cursory look from someone not familiar with the
> regulator stuff, maybe we can make it compatible with old DTS by adding
> the new names as aliases ({devm_,}regulator_register_supply_alias?) as
> "vin" or "buck5", if we see the old vin-supply definitions?
>

We can do that of course. My hesitation is, however, it makes the driver take
extra code which may not be needed once all .dts files have been updated. The
driver code will be left there forever.

BR,
Guodong Xu