Re: [PATCH v2 3/3] watchdog:rit_wdt: Add support for WDIOF_CARDRESET

[Jan Kiszka]

On 12.07.23 08:05, Li, Hua Qian (DI FA CTR IPC CN PRC4) wrote:
> On Tue, 2023-07-11 at 22:01 -0700, Guenter Roeck wrote:
>> On a higher level, the entire code puzzles me. Obviously there
>> must be a means for the BIOS or ROMMON to write PON_REASON_SOF_NUM
>> into some memory area. That means the BIOS/ROMMON must be able
>> to detect that situation. Why not use the same code to detect this
>> in the driver without the complexity of passing it from BIOS/ROMMON
>> to driver in some random memory area ?
>>
> In TI AM65x cases, the hardware is not capable of issuing a reset on
> its own, and is not possible to record or detect the watchdog reset
> situation. So `k3-rit-wdt` firmware which runs in a mcu core was used
> to detect the watchdog interrupt and reset the Soc. Here I am trying to
> write the reason in this firmware when watchdog interrupt happens, and
> read it out in kernel.

See https://github.com/siemens/k3-rti-wdt/issues/1 for where this
started and where the firmware part comes into play.

I still wonder why we couldn't have had a nicer hardware watchdog
instead but this can't be changed anymore.

Jan

-- 
Siemens AG, Technology
Competence Center Embedded Linux