arm64: dts: st: fix arm,smc-id of the SMC watchdog on stm32mp2

[PATCH] arm64: dts: st: fix arm,smc-id of the SMC watchdog on stm32mp2

Posted by Mateusz Nowicki 2 weeks, 4 days ago

OP-TEE implements the STM32MP2 watchdog SMC service with function ID
0xbc000000 (CFG_WDT_SM_HANDLER_ID), not 0xb200005a. With the current
value the arm_smc_wdt probe fails with -EIO and the IWDG started by the
bootloader is never refreshed.

Fixes: 89fca38168c9 ("arm64: dts: st: add arm-wdt node for watchdog support on stm32mp251")
Fixes: e9b03ef21386 ("arm64: dts: st: introduce stm32mp23 SoCs family")
Signed-off-by: Mateusz Nowicki <mateusz.nowicki@posteo.net>
---
 arch/arm64/boot/dts/st/stm32mp231.dtsi | 2 +-
 arch/arm64/boot/dts/st/stm32mp251.dtsi | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/st/stm32mp231.dtsi b/arch/arm64/boot/dts/st/stm32mp231.dtsi
index 9e1d240888ff..35e247af957c 100644
--- a/arch/arm64/boot/dts/st/stm32mp231.dtsi
+++ b/arch/arm64/boot/dts/st/stm32mp231.dtsi
@@ -35,7 +35,7 @@ arm-pmu {
 
 	arm_wdt: watchdog {
 		compatible = "arm,smc-wdt";
-		arm,smc-id = <0xb200005a>;
+		arm,smc-id = <0xbc000000>;
 		status = "disabled";
 	};
 
diff --git a/arch/arm64/boot/dts/st/stm32mp251.dtsi b/arch/arm64/boot/dts/st/stm32mp251.dtsi
index 9c63fdb5a885..2dcbba65e298 100644
--- a/arch/arm64/boot/dts/st/stm32mp251.dtsi
+++ b/arch/arm64/boot/dts/st/stm32mp251.dtsi
@@ -36,7 +36,7 @@ arm-pmu {
 
 	arm_wdt: watchdog {
 		compatible = "arm,smc-wdt";
-		arm,smc-id = <0xb200005a>;
+		arm,smc-id = <0xbc000000>;
 		status = "disabled";
 	};
 
-- 
2.55.0

Re: [PATCH] arm64: dts: st: fix arm,smc-id of the SMC watchdog on stm32mp2

Posted by Mateusz Nowicki 2 days, 11 hours ago

Hi Alexandre,

Gentle ping on this fix, Antonio gave his Reviewed-by on Sep 8.

On current stm32-next the SMC watchdog still fails to probe on the
STM32MP257F-DK:

    arm_smc_wdt watchdog: probe with driver arm_smc_wdt failed with error -5

Could you take it for v7.4?

Thanks,
Mateusz

Re: [Linux-stm32] [PATCH] arm64: dts: st: fix arm, smc-id of the SMC watchdog on stm32mp2

Posted by Antonio Borneo 2 weeks, 3 days ago

On Mon, 2026-09-07 at 09:14 +0000, Mateusz Nowicki wrote:
> OP-TEE implements the STM32MP2 watchdog SMC service with function ID
> 0xbc000000 (CFG_WDT_SM_HANDLER_ID), not 0xb200005a. With the current
> value the arm_smc_wdt probe fails with -EIO and the IWDG started by the
> bootloader is never refreshed.
> 
> Fixes: 89fca38168c9 ("arm64: dts: st: add arm-wdt node for watchdog support on stm32mp251")
> Fixes: e9b03ef21386 ("arm64: dts: st: introduce stm32mp23 SoCs family")
> Signed-off-by: Mateusz Nowicki <mateusz.nowicki@posteo.net>

Reviewed-by: Antonio Borneo <antonio.borneo@foss.st.com>

Thanks,
Antonio