[PATCH 1/2] dt-bindings: soc: samsung: exynos-pmu: remove syscon for google,gs101-pmu

[Peter Griffin]

Hi Krzysztof,

On Wed, 5 Nov 2025 at 08:55, Krzysztof Kozlowski <krzk at kernel.org> wrote:
>
> On Mon, Nov 03, 2025 at 08:03:10AM +0000, Peter Griffin wrote:
> > Since commit ba5095ebbc7a ("mfd: syscon: Allow syscon nodes without a
> > "syscon" compatible") it is possible to register a regmap without the
> > syscon compatible in the node.
> >
> > Update the bindings for google,gs101-pmu so that the syscon compatible is
>
> That's an ABI break...
>
> > no longer required. As it isn't really correct to claim we are compatible with
> > syscon (as a mmio regmap created by syscon will not work on gs101).
>
> ... with kind of a reason, but then the question I have: was the
> standard MMIO regmap exposed via syscon ever working for any part of
> this PMU?
>
> Original posting here:
> https://lore.kernel.org/all/20231209233106.147416-2-peter.griffin@linaro.org/
> did not change PMU driver and did not express that the syscon is broken.

With the benefit of hindsight, no, PMU write register access was never
working for any part of the PMU.

On the initial posting I didn't hit this as we were only disabling the
Watchdog on boot (which doesn't write any PMU registers). Once the
issue with accessing PMU regs became clear, I first suspected some
missing clock. Then later it became apparent we needed a SMC call and
after some initial proposals the syscon driver was enhanced with the
of_syscon_register_regmap() API in 769cb63166d9 ("mfd: syscon: Add
of_syscon_register_regmap() API"). At the time that commit was merged,
syscon driver required a "syscon" compatible, but since ba5095ebbc7a
("mfd: syscon: Allow syscon nodes without a "syscon" compatible") that
is no longer the case.

Peter.