I updated my IBM M5105/LSI 9260i card (data partitions only, not boot drive) from v12.15.0-0239 using the MegaRAID Storage Manager utility in Windows whilst online with no issues, and it fixed a bug I'd started getting where the drives kept disappearing requiring a full power-off to restore.
I found a slightly newer firmware version here: https://support.lenovo.com/us/en/downloads/ds040844-firmware-for-avago-…
I updated my IBM M5105/LSI 9260i card (data partitions only, not boot drive) from v12.15.0-0239 using the MegaRAID Storage Manager utility in Windows whilst online with no issues, and it fixed a bug I'd started getting where the drives kept disappearing requiring a full power-off to restore.