[PATCH] arm64: dts: exynos850: Add syscon-poweroff node

[PATCH] arm64: dts: exynos850: Add syscon-poweroff node

[Alexey Klimov]

Without poweroff node Exynos850-based board continue to draw current
(around ~60 mA with my test setup) after poweroff. Kernel also reports
different lockup problems and RCU stalls warnings continuosly after
last kernel messages about hardware being switched off.
Turns out we missed a write to PMU's PS_HOLD_CONTROL (PMU + 0x30c)
register that actually switches the SoC off.

Add poweroff node that implements this.

With this change the current draw after power off is in range of few
milliampers and lockup messages are no more.

Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
---
 arch/arm64/boot/dts/exynos/exynos850.dtsi | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm64/boot/dts/exynos/exynos850.dtsi b/arch/arm64/boot/dts/exynos/exynos850.dtsi
index cb55015c8dce..3881f573ec08 100644
--- a/arch/arm64/boot/dts/exynos/exynos850.dtsi
+++ b/arch/arm64/boot/dts/exynos/exynos850.dtsi
@@ -215,6 +215,13 @@ pmu_system_controller: system-controller@11860000 {
 			compatible = "samsung,exynos850-pmu", "syscon";
 			reg = <0x11860000 0x10000>;
 
+			poweroff: syscon-poweroff {
+				compatible = "syscon-poweroff";
+				offset = <0x30c>; /* PS_HOLD_CONTROL */
+				mask = <0x00000100>;
+				value = <0x0>;
+			};
+
 			reboot: syscon-reboot {
 				compatible = "syscon-reboot";
 				regmap = <&pmu_system_controller>;

---
base-commit: 85964cdcad0fac9a0eb7b87a0f9d88cc074b854c
change-id: 20260325-exynos850-poweroff-a6515334888a

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

Re: [PATCH] arm64: dts: exynos850: Add syscon-poweroff node

[Alexey Klimov]

On Wed Mar 25, 2026 at 12:26 AM GMT, Alexey Klimov wrote:
> Without poweroff node Exynos850-based board continue to draw current
> (around ~60 mA with my test setup) after poweroff. Kernel also reports
> different lockup problems and RCU stalls warnings continuosly after
> last kernel messages about hardware being switched off.
> Turns out we missed a write to PMU's PS_HOLD_CONTROL (PMU + 0x30c)
> register that actually switches the SoC off.
>
> Add poweroff node that implements this.
>
> With this change the current draw after power off is in range of few
> milliampers and lockup messages are no more.
>
> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
> ---
>  arch/arm64/boot/dts/exynos/exynos850.dtsi | 7 +++++++

Any feedback on this?

BR,
Alexey

Re: [PATCH] arm64: dts: exynos850: Add syscon-poweroff node

[Krzysztof Kozlowski]

On 20/04/2026 17:04, Alexey Klimov wrote:
> On Wed Mar 25, 2026 at 12:26 AM GMT, Alexey Klimov wrote:
>> Without poweroff node Exynos850-based board continue to draw current
>> (around ~60 mA with my test setup) after poweroff. Kernel also reports
>> different lockup problems and RCU stalls warnings continuosly after
>> last kernel messages about hardware being switched off.
>> Turns out we missed a write to PMU's PS_HOLD_CONTROL (PMU + 0x30c)
>> register that actually switches the SoC off.
>>
>> Add poweroff node that implements this.
>>
>> With this change the current draw after power off is in range of few
>> milliampers and lockup messages are no more.
>>
>> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
>> ---
>>  arch/arm64/boot/dts/exynos/exynos850.dtsi | 7 +++++++
> 
> Any feedback on this?

You posted it right before closing tree, so this was waiting for a few
days for anyone to chime in and then tree is closed. It's merge window
now, so I don't review anything. Nothing new here...

Best regards,
Krzysztof

Re: [PATCH] arm64: dts: exynos850: Add syscon-poweroff node

[Krzysztof Kozlowski]

On 20/04/2026 17:18, Krzysztof Kozlowski wrote:
> On 20/04/2026 17:04, Alexey Klimov wrote:
>> On Wed Mar 25, 2026 at 12:26 AM GMT, Alexey Klimov wrote:
>>> Without poweroff node Exynos850-based board continue to draw current
>>> (around ~60 mA with my test setup) after poweroff. Kernel also reports
>>> different lockup problems and RCU stalls warnings continuosly after
>>> last kernel messages about hardware being switched off.
>>> Turns out we missed a write to PMU's PS_HOLD_CONTROL (PMU + 0x30c)
>>> register that actually switches the SoC off.
>>>
>>> Add poweroff node that implements this.
>>>
>>> With this change the current draw after power off is in range of few
>>> milliampers and lockup messages are no more.
>>>
>>> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
>>> ---
>>>  arch/arm64/boot/dts/exynos/exynos850.dtsi | 7 +++++++
>>
>> Any feedback on this?
> 
> You posted it right before closing tree, so this was waiting for a few
> days for anyone to chime in and then tree is closed. It's merge window
> now, so I don't review anything. Nothing new here...

... and the pull to SoC actually happened before. It's public, so you
could check that.

Best regards,
Krzysztof