linux-kernel - [PATCH v2 2/2] arm64: dts: exynos: gs101: remove syscon compatible from pmu node

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Message-Id: <20251114-remove-pmu-syscon-compat-v2-2-9496e8c496c7@linaro.org>
Date: Fri, 14 Nov 2025 12:00:17 +0000
From: Peter Griffin <peter.griffin@...aro.org>
To: 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>
Cc: linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 kernel-team@...roid.com, willmcvicker@...gle.com, dan.carpenter@...aro.org, 
 arnd@...db.de, robh@...nel.org, Peter Griffin <peter.griffin@...aro.org>
Subject: [PATCH v2 2/2] arm64: dts: exynos: gs101: remove syscon compatible
 from pmu node

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.

As mentioned in that commit, it's not correct to claim we are compatible
with syscon, as a MMIO regmap created by syscon won't work. Removing the
syscon compatible means syscon driver won't ever create a mmio regmap.

Note this isn't usually an issue today as exynos-pmu runs at an early
initcall so the custom regmap will have been registered first. However
changes proposed in [1] will bring -EPROBE_DEFER support to syscon allowing
this mechanism to be more robust, especially in highly modularized systems.

Technically this is a ABI break but no other platforms are
affected. Additionally (with the benefit of hindsight) a MMIO syscon has
never worked for PMU register writes, thus the ABI break is justified.

Link: https://lore.kernel.org/lkml/aQdHmrchkmOr34r3@stanley.mountain/ [1]
Signed-off-by: Peter Griffin <peter.griffin@...aro.org>
---
Changes in v2:
 - Update commit message (Krzysztof)
---
 arch/arm64/boot/dts/exynos/google/gs101.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/exynos/google/gs101.dtsi b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
index d06d1d05f36408137a8acd98e43d48ea7d4f4292..e1a7d33fd4a369f7b352b81d2070beb62a0ced16 100644
--- a/arch/arm64/boot/dts/exynos/google/gs101.dtsi
+++ b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
@@ -1705,7 +1705,7 @@ sysreg_apm: syscon@...20000 {
 		};

 		pmu_system_controller: system-controller@...60000 {
-			compatible = "google,gs101-pmu", "syscon";
+			compatible = "google,gs101-pmu";
 			reg = <0x17460000 0x10000>;
 			google,pmu-intr-gen-syscon = <&pmu_intr_gen>;

-- 
2.52.0.rc1.455.g30608eb744-goog