From: Murillo Fernandes Bernardes <bernarde@br.ibm.com>
Date: Fri, 10 Aug 2007 20:31:00 +0000 (+0200)
Subject: x86_64: Calgary - Fix mis-handled PCI topology
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=f055a0619aae795832ef6a783021184925758b67;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git

x86_64: Calgary - Fix mis-handled PCI topology

Current code assumed that devices were directly connected to a Calgary
bridge, as it tried to get the iommu table directly from the parent bus
controller.

When we have another bridge between the Calgary/CalIOC2 bridge and the
device we should look upwards until we get to the top (Calgary/CalIOC2
bridge), where the iommu table resides.

Signed-off-by: Murillo Fernandes Bernardes <mfb@br.ibm.com>
Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/arch/x86_64/kernel/pci-calgary.c b/arch/x86_64/kernel/pci-calgary.c
index ba16c968ca3..71da01e73f0 100644
--- a/arch/x86_64/kernel/pci-calgary.c
+++ b/arch/x86_64/kernel/pci-calgary.c
@@ -367,16 +367,15 @@ static inline struct iommu_table *find_iommu_table(struct device *dev)
 
 	pdev = to_pci_dev(dev);
 
-	/* is the device behind a bridge? */
-	if (unlikely(pdev->bus->parent))
-		pbus = pdev->bus->parent;
-	else
-		pbus = pdev->bus;
+	pbus = pdev->bus;
+
+	/* is the device behind a bridge? Look for the root bus */
+	while (pbus->parent)
+		pbus = pbus->parent;
 
 	tbl = pci_iommu(pbus);
 
-	BUG_ON(pdev->bus->parent &&
-	       (tbl->it_busno != pdev->bus->parent->number));
+	BUG_ON(tbl && (tbl->it_busno != pbus->number));
 
 	return tbl;
 }