[PATCH 5.10.y] scsi: aic7xxx: Use default settings on the SGI O2 onboard controllers

[Sasha Levin <sashal@kernel.org>]

From: Imre Kaloz <kaloz@kernel.org>

[ Upstream commit 696bdfc58975fbc70d2e2347a74e0b562e7e2494 ]

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>
Link: https://patch.msgid.link/20261026131432.26065-1-kaloz@kernel.org
Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
[ sashal: Adjusted context in ahc_init() to preserve an existing tab on the blank line after the host-ID assignment. ]
Signed-off-by: Sasha Levin <sashal@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 12fed15dec66f..a6b18547df7d7 100644
--- a/drivers/scsi/aic7xxx/aic7xxx_core.c
+++ b/drivers/scsi/aic7xxx/aic7xxx_core.c
@@ -5267,9 +5267,13 @@ 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 656f680c78024..7db8e20aff5c4 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);
-- 
2.53.0