int megaraid_detect (Scsi_Host_Template * host_template);
host_template - Our soft state maintained by mid-layer
the detect entry point for the mid-layer. We scan the PCI bus for our controllers and start them.
PCI_DEVICE_ID_PERC4_DI below represents the PERC4/Di class of products. All of them share the same vendor id, device id, and subsystem vendor id but different subsystem ids. As of now, driver does not use the subsystem id.