Hi Sandeep
-----Original Message----- From: Sandeep Tripathy sandeep.tripathy@broadcom.com Sent: 27 August 2020 16:38
On Thu, Aug 27, 2020 at 8:31 PM Dan Handley via TF-A <tf- a@lists.trustedfirmware.org> wrote:
Arm development platforms that have an SBSA secure watchdog like N1SDP do
not register an interrupt handler for the WS0 signal. They simply wait for the WS1 signal, which is fed to a higher agent (in this case the System Control Processor), which resets the platform.
There is no explicit watchdog interrupt handling functionality in TF-A.
what happens to non secure sbsa WS1 ?
Sorry, I missed that you were talking about NS WS1 as well.
That is the case for Secure sbsa WS1. NS WS0 ----> EL1 X (optional) but linux already implements it . NS WS1 ----> EL3 X TF-A Do not handle it. Hence the patch. Not handling it altogether is not an option I guess.
Yes, you're right.
Platform callback can optionally do more things like some logging.
Fair enough.
Ultimately 'system_reset2' seems to be the thing everyone would like to do as part of action. Then to reduce duplicate code we can have at one place.
But system_reset2 takes arguments, which might vary between platforms. Best to leave it to the platform hook I think. I guess there could be a default weak definition that does an architectural warm reset, although I'm not sure what the policy is these days on weak symbols.
The rare lockup of core where it's not able to respond (not the software ones) requires some other agent to detect and reset/recover the system. Linux watchdog (ns sbsa WS1) will go unnoticed in such cases. ie. even if the watchdog hardware detected the lockup and indicated by WS0 then WS1 .. both were not acted upon. If it were the secure watchdog then no issues.
+1.
Regards
Dan.