SATA Miniport driver

Hi All,
I am writing a SCSI miniport driver that controls the PC’s onboard SATA
controller. In “combined” mode everything works just fine but when I
configure the system to run in PCI “native” mode the disk interrupt is
coming through very slowly (e.g.: I issue a Read Sectors command for a
single sector and it takes several seconds before the interrupt handler is
evoked). In the meanwhile I get the infamous SCSI Port message: Sp

In my Find Adapter routine I have tried several things with respect to
setting the Interrupt Line, Interrupt Level, and Interrupt Vector values but
nothing seems to change.

Does anyone have any idea as to what needs to be done here?

Thanks in advance,