On Wed, 17 Nov 2021 16:20:58 +0530, Sreekanth Reddy wrote:

While determining the SAS address of a drive, the driver checks whether
the handle number is less than the HBA phys count or not.
If the handle number is less than the HBA phy’s count then driver
assumes that this handle belongs to HBA and hence it assigns the
HBA SAS address.
During IOC firmware downgrade operation, if the number of HBA phys got
reduced and the OS drive’s device handle falls below start of the day
HBA phys count then while determining the OS drive’s SAS address
driver uses the HBA SAS address. This leads to a mismatch of drive’s
SAS address and hence the driver unregisters the OS drive and the
system falls into read only mode.

[...]

Applied to 5.16/scsi-fixes, thanks!

[1/1] mpt3sas: Fix system falling into readonly mode
      https://git.kernel.org/mkp/scsi/c/91202a01a2fb

-- 
Martin K. Petersen	Oracle Linux Engineering