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

[Imre Kaloz <kaloz@kernel.org>]

The SGI O2 firmware runs its onboard aic7880s without the Adaptec BIOS,
so scratch RAM holds no settings. The left over BIOS path reads
uninitialised bytes, and bad parity panics the boot.

Use the defaults there with host ID 0. ahc_init() keeps the default host
ID ahc_pci_config() chose, 7 on other PCI controllers, so only the O2
changes.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Imre Kaloz <kaloz@kernel.org>
---
 drivers/scsi/aic7xxx/aic7xxx_core.c |  8 ++++++--
 drivers/scsi/aic7xxx/aic7xxx_pci.c  | 20 +++++++++++++++++++-
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/aic7xxx/aic7xxx_core.c b/drivers/scsi/aic7xxx/aic7xxx_core.c
index b9761f9f0bbc..8ad82171e925 100644
--- a/drivers/scsi/aic7xxx/aic7xxx_core.c
+++ b/drivers/scsi/aic7xxx/aic7xxx_core.c
@@ -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.
diff --git a/drivers/scsi/aic7xxx/aic7xxx_pci.c b/drivers/scsi/aic7xxx/aic7xxx_pci.c
index 2d4c85426dc3..5a04c7d55e4b 100644
--- a/drivers/scsi/aic7xxx/aic7xxx_pci.c
+++ b/drivers/scsi/aic7xxx/aic7xxx_pci.c
@@ -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);
-- 
2.47.3