scsi: aic7xxx: Use default settings on the SGI O2 onboard controllers

index b9761f9f0bbc..8ad82171e925 100644
@@ -5266,9 +5266,13 @@ ahc_init(struct ahc_softc *ahc)
 
 	/*
 	 * Assume we have a board at this stage and it has been reset.
+	 * PCI controllers keep the host ID ahc_pci_config() chose.
 	 */
-	if ((ahc->flags & AHC_USEDEFAULTS) != 0)
-		ahc->our_id = ahc->our_id_b = 7;
+	if ((ahc->flags & AHC_USEDEFAULTS) != 0) {
+		if ((ahc->chip & AHC_PCI) == 0)
+			ahc->our_id = 7;
+		ahc->our_id_b = 7;
+	}
 
 	/*
 	 * Default to allowing initiator operations.

index 2d4c85426dc3..5a04c7d55e4b 100644
@@ -701,6 +701,21 @@ ahc_find_pci_device(ahc_dev_softc_t pci)
 	return (NULL);
 }
 
+/*
+ * The SGI O2 firmware runs its onboard controllers, in slots 1 and 2 of the
+ * root bus, without the Adaptec BIOS and at host ID 0.  It leaves no settings
+ * in scratch RAM, which may still hold power-on contents with bad parity.
+ */
+static bool
+ahc_pci_sgi_o2_onboard(struct ahc_softc *ahc)
+{
+	int slot = ahc_get_pci_slot(ahc->dev_softc);
+
+	return IS_ENABLED(CONFIG_SGI_IP32) &&
+	       ahc_get_pci_bus(ahc->dev_softc) == 0 &&
+	       (slot == 1 || slot == 2);
+}
+
 int
 ahc_pci_config(struct ahc_softc *ahc, const struct ahc_pci_identity *entry)
 {

@@ -782,6 +797,9 @@ ahc_pci_config(struct ahc_softc *ahc, const struct ahc_pci_identity *entry)
 	ahc->bus_intr = ahc_pci_intr;
 	ahc->bus_chip_init = ahc_pci_chip_init;
 
+	if (ahc_pci_sgi_o2_onboard(ahc))
+		ahc->flags |= AHC_NO_BIOS_INIT;
+
 	/* Remember how the card was setup in case there is no SEEPROM */
 	if ((ahc_inb(ahc, HCNTRL) & POWRDN) == 0) {
 		ahc_pause(ahc);

@@ -898,7 +916,7 @@ ahc_pci_config(struct ahc_softc *ahc, const struct ahc_pci_identity *entry)
 			 * Assume only one connector and always turn
 			 * on termination.
 			 */
- 			our_id = 0x07;
+			our_id = ahc_pci_sgi_o2_onboard(ahc) ? 0 : 0x07;
 			sxfrctl1 = STPWEN;
 		}
 		ahc_outb(ahc, SCSICONF, our_id|ENSPCHK|RESET_SCSI);