FAILED: patch "[PATCH] scsi: aic7xxx: Use default settings on the SGI O2 onboard controllers" failed to apply to 5.10-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 696bdfc58975fbc70d2e2347a74e0b562e7e2494
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261109202514-failed-5.10-696bdfc58975@kernel.org' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 696bdfc58975fbc70d2e2347a74e0b562e7e2494 Mon Sep 17 00:00:00 2001
From: Imre Kaloz <kaloz@kernel.org>
Date: Mon, 26 Oct 2026 14:14:32 +0100
Subject: [PATCH] scsi: aic7xxx: Use default settings on the SGI O2 onboard
 controllers

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>
---
 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 db330ca927678..af6115bfb2808 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 2d4c85426dc3e..5a04c7d55e4b5 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