linux-kernel - Re: [PATCH v5 1/4] dt-bindings: clock: google,gs101-clock: add samsung,sysreg property as required

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Message-ID: <176359741364.3604013.10884169748220916434.robh@kernel.org>
Date: Wed, 19 Nov 2025 18:10:14 -0600
From: "Rob Herring (Arm)" <robh@...nel.org>
To: Peter Griffin <peter.griffin@...aro.org>
Cc: Chanwoo Choi <cw00.choi@...sung.com>, linux-samsung-soc@...r.kernel.org,
	Krzysztof Kozlowski <krzk+dt@...nel.org>, linux-clk@...r.kernel.org,
	Will McVicker <willmcvicker@...gle.com>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Stephen Boyd <sboyd@...nel.org>, kernel-team@...roid.com,
	Sam Protsenko <semen.protsenko@...aro.org>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Michael Turquette <mturquette@...libre.com>,
	Tudor Ambarus <tudor.ambarus@...aro.org>,
	Alim Akhtar <alim.akhtar@...sung.com>,
	linux-arm-kernel@...ts.infradead.org,
	Krzysztof Kozlowski <krzk@...nel.org>,
	André Draszik <andre.draszik@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>
Subject: Re: [PATCH v5 1/4] dt-bindings: clock: google,gs101-clock: add
 samsung,sysreg property as required


On Fri, 14 Nov 2025 14:16:48 +0000, Peter Griffin wrote:
> Each CMU (with the exception of cmu_top) has a corresponding sysreg bank
> that contains the BUSCOMPONENT_DRCG_EN and optional MEMCLK registers.
> The BUSCOMPONENT_DRCG_EN register enables dynamic root clock gating of
> bus components and MEMCLK gates the sram clock.
> 
> Now the clock driver supports automatic clock mode, to fully enable dynamic
> root clock gating it is required to configure these registers. Update the
> bindings documentation so that all CMUs (with the exception of
> gs101-cmu-top) have samsung,sysreg as a required property.
> 
> Note this is NOT an ABI break, as if the property isn't specified the
> clock driver will fallback to the current behaviour of not initializing
> the registers. The system still boots, but bus components won't benefit
> from dynamic root clock gating and dynamic power will be higher (which has
> been the case until now anyway).
> 
> Additionally update the DT example to included the correct CMU size as
> registers in that region are used for automatic clock mode.
> 
> Signed-off-by: Peter Griffin <peter.griffin@...aro.org>
> ---
> Changes in v5:
> - Invert the test for google,gs101-cmu-top (Andre)
> 
> Changes in v4
> - Update commit description with additional requested details (Krzysztof)
> 
> Changes in v3:
> - Update commit description as to why the sysreg is required (Krzysztof)
> 
> Changes in v2:
> - Update commit description regarding updated example (Andre)
> ---
>  .../devicetree/bindings/clock/google,gs101-clock.yaml | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 

Reviewed-by: Rob Herring (Arm) <robh@...nel.org>