Salvatore,
So I believe the right thing would be to revert first in the stable series where it was applied (5.10.y, 5.15.y) the commit e0e0747de0ea ("scsi: mpt3sas: Fix return value check of dma_get_required_mask()") and then on top of this revert apply the patches:
9df650963bf6 ("scsi: mpt3sas: Don't change DMA mask while reallocating pools") 1a2dcbdde82e ("scsi: mpt3sas: re-do lost mpt3sas DMA mask fix") 06e472acf964 ("scsi: mpt3sas: Remove usage of dma_get_required_mask() API")
Attached mbox file implements this.
Does that looks now good for resolving the regression?
Yes, that's one way to resolve it.
At a quick glance your mbox looks fine. Best way to validate would be to compare the resulting _base_config_dma_addressing() function between your tree and upstream. I don't believe we have had additional changes here so there should be no delta.