I'm use the Gen10 DL20 server too,
The E208 or P408 all call smart array Gen10
It doesn't use switch mode between HBA or Raid. Now HPE use Mixed mode to use HBA disk and Raid disk in same card with same SAS port.

When use add a disk without create new array to init it, it will be the HBA mode to through Disk to OS.
I use the bios mean of my E204i-a card.
I connect two SSD disk to it. one are use create array mode to use it for Raid0 mode, other one not create array.
So one disk show use Raid mode , and associated to array xx
other one not use raid array:
it show HBA mode , and direct show the disk temperature.