pysmurf-controller: Return status from RssiRestart in session.data

[tristpinsm]

Check that the system is responsive after the RSSI restart.

Description

According to the instructions here, the RSSI lane being locked up can be identified by querying a given register. This PR performs this check after triggering the RSSI restart to confirm that it was successful and returns the result.

Motivation and Context

Suggested in #875. It will alert the user if the system is still unresponsive after the restart, or may be useful to rule out an RSSI lock-up when trying to identify an issue by confirming that it is responsive.

How Has This Been Tested?

Tested at SLAC to confirm that the register is read successfully and the return value is as expected. Not tested on a locked-up system.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[BrianJKoopman]

Looks good to me, just need to document the session.data structure in the docstring. Thanks!

[msilvafe]

I think it may be helpful to call the caget twice once before and once after the restart_rssi script is called. Or have a separate task called check_rssi_status or something similar that can be called before the restart_rssi task. I suggest this because folks have called this when the problem possibly wasn’t an rssi lockup in which case it’s helpful to know if the caget was properly returning before running restart_rssi or only after

[BrianJKoopman]

One other small suggested change. Otherwise this looks good to me. @msilvafe?

[msilvafe]

Looks good to me, thanks @tristpinsm