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

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Message-ID: <20251112-airborne-tungsten-chupacabra-1c668c@kuoka>
Date: Wed, 12 Nov 2025 11:20:54 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Peter Griffin <peter.griffin@...aro.org>
Cc: André Draszik <andre.draszik@...aro.org>, 
	Tudor Ambarus <tudor.ambarus@...aro.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Alim Akhtar <alim.akhtar@...sung.com>, linux-arm-kernel@...ts.infradead.org, 
	linux-samsung-soc@...r.kernel.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	dan.carpenter@...aro.org, kernel-team@...roid.com, willmcvicker@...gle.com, arnd@...db.de
Subject: Re: [PATCH 1/2] dt-bindings: soc: samsung: exynos-pmu: remove syscon
 for google,gs101-pmu

On Tue, Nov 11, 2025 at 10:18:47AM +0000, Peter Griffin wrote:
> Hi Krzysztof,
> 
> On Wed, 5 Nov 2025 at 08:55, Krzysztof Kozlowski <krzk@...nel.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.

Please add it to the last paragraph of your commit msg, that this was
never working in practice thus changing ABI is justified.

Best regards,
Krzysztof