On 7/12/2021 3:57 PM, Jan Kiszka wrote:
On 12.07.21 15:37, Cedric Hombourger wrote:
SIMATIC IPCs 227E/277E share the same external watchdog (SCH5347)
than the IPC 4x7Es we already support. Initialization of the
SAFE_EN_N line differs a bit and was therefore moved to separate
setup functions. Programming and enabling of the timeout is the
same and is now handled in set_timeout(). With this change, both
Linux and efibootguard would use the same chip and no longer
depend on the built-in iTCO watchdog.
The 4x7E had a hard requirement to use platform watchdog rather than
iTCO - because the latter was unable to actually reset the device. This
limitation does not exist on the 2x7E series. Your commit message is
lacking a reasoning why a user should use that special watchdog, rather
than the working and widely supported iTCO?
Well I do not have a reason other than the Simatic IPC team "insisting"
on us using the external one via their simatic-ipc-wdt driver. We have
indeed found both watchdogs to be working just fine. However having
efibootguard initializing the built-in watchdog (iTCO) and Linux
blacklisting iTCO and using simatic-ipc-wdt (as instructed) is simply
asking for troubles (IMO).
If you believe we can push back and use the iTCO across the board, I am
all for it and both of us could talk to Florian S and maybe have his
team update the simatic-ipc-lsp documentation to make it clear that the
iTCO driver may safely be used on 227E (as we both found)
Let me know if you have other ideas or suggestions
Cedric
Jan
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