[PATCH 0/2] Exynos850: Add ACPM node and enable cpufreq

[Alexey Klimov]

This series adds the ACPM IPC firmware node and CPUs operating performance
points for the Exynos850 SoC, switching CPU clock sources to the ACPM DVFS
clocks to enable cpufreq. Exynos850 has two clusters with four Cortex-A55
cores each with identical OPPs.

In theory, we could have two OPPs above known nominal max frequency (2Ghz)
but in practice the board becomes unstable with fully loaded CPU-bound
tasks and hangs pretty quickly on OPPs above 2 Ghz:

	opp-2106000000 {
		opp-hz = /bits/ 64 <2106000000>;
		opp-microvolt = <1106250>;
		clock-latency-ns = <500000>;
	};

	opp-2210000000 {
		opp-hz = /bits/ 64 <2210000000>;
		opp-microvolt = <1181250>;
		clock-latency-ns = <500000>;
	};

with random data aborts and illegal instructions. Maybe SoC can survive
short bursts to these frequencies but this requires a bit more messing
around with cpufreq_dt.

Also, it is currently unstable on 2.002 GHz OPP as well so this one
excluded from the series too:

	opp-2002000000 {
		opp-hz = /bits/ 64 <2002000000>;
		opp-microvolt = <1050000>;
		clock-latency-ns = <500000>;
	};

with the same symptoms but takes much longer (~1..2 hr) to reproduce on
E850-96 WinLink board.

Sustained testing overnight confirmed stability up to 1.846 GHz
(opp-1846000000). Higher OPPs are omitted for now and can be evaluated
when we will have thermal zones.

The dependency for this series is:
https://lore.kernel.org/linux-samsung-soc/20260929-exynos850-acpm-firmware-support-v3-0-473a69fc8a3d@xxxxxxxxxx/

Signed-off-by: Alexey Klimov <alexey.klimov@xxxxxxxxxx>
---
Alexey Klimov (2):
      arm64: dts: exynos850: Add ACPM firmware node
      arm64: dts: exynos850: Add operating points for CPUs and enable cpufreq

 arch/arm64/boot/dts/exynos/exynos850.dtsi | 237 +++++++++++++++++++++++++++++-
 1 file changed, 233 insertions(+), 4 deletions(-)
---
base-commit: 5a956dde5526a634dca7ccad27c051ebcc306089
change-id: 20260929-exynos850-acpm-node-cpufreq-33819039cf43
prerequisite-message-id: 20260929-exynos850-acpm-firmware-support-v3-0-473a69fc8a3d@xxxxxxxxxx
prerequisite-patch-id: 5a3c87e368d6bac968f16a0e56fcff5eaec60dea
prerequisite-patch-id: 8d6d1564a919eca361aef19af5dbe1cf3205198e

Best regards,
-- 
Alexey Klimov <alexey.klimov@xxxxxxxxxx>