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

[Marek Vasut <marex@nabladev.com>]

On 10/31/26 1:00 PM, mateusz.nowicki@posteo.net wrote:

Hello Mateusz,

> Marek, would that work for the DHCOS boards? I can send the patch if
> you tell me which of them ship the old OP-TEE. Your OP-TEE change to
> accept both IDs is a good mitigation on top of it for anybody who
> updates the firmware.

I do not think revert of this patch is the right approach here. I also 
do not think patching the arm,smc-id in board DT is the right approach. 
Both of those, because we do not know which SMC ID is the correct one 
(we do not know which firmware is running and how it is configured, see 
the OP-TEE OS CFG_WDT_SM_HANDLER_ID which is user configurable, and as 
far as I can tell, the SMC ID is not discoverable, or is it?).

But maybe there is some way to probe for the correct ARM SMC WDT ID ? (I 
do not think we can infer the ID from e.g. OP-TEE OS version, because of 
the CFG_WDT_SM_HANDLER_ID user configuration).

In case of this SoC, we can mostly assume that the SMC IDs will be one 
of the two, 0xb200005a or 0xbc000000, so maybe we can extend the SMC WDT 
driver to support some sort of fallback -- if the primary SMC ID fails 
as not supported, try the secondary one ?

As for the DHCOS boards, those are evalboards, their bootloader can be 
easily updated, and they are running recent software more often than 
not, there this topic is mostly a non-issue. There is however hardware 
which does have downstream DTs which pull in upstream DTSIs .