linux-kernel - [PATCH v2] iommu/of: Remove PCI host bridge node check

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Message-Id: <56a797382ffc65243169205c36d9f9fb1173dddd.1505989095.git.robin.murphy@arm.com>
Date:   Thu, 21 Sep 2017 11:20:58 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     joro@...tes.org
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        jean-philippe.brucker@....com
Subject: [PATCH v2] iommu/of: Remove PCI host bridge node check

of_pci_iommu_init() tries to be clever and stop its alias walk at the
device represented by master_np, in case of weird PCI topologies where
the bridge to the IOMMU and the rest of the system is not at the root.
It turns out this is a bit short-sighted, since there are plenty of
other callers of pci_for_each_dma_alias() which would also need the same
behaviour in that situation, and the only platform so far with such a
topology (Cavium ThunderX2) already solves it more generally via a PCI
quirk. As this check is effectively redundant, and returning a boolean
value as an int is a bit broken anyway, let's just get rid of it.

Reported-by: Jean-Philippe Brucker <jean-philippe.brucker@....com>
Signed-off-by: Robin Murphy <robin.murphy@....com>
---

Ugh, I'm really failing to spot the obvious today...

 drivers/iommu/of_iommu.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index e60e3dba85a0..50947ebb6d17 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -157,10 +157,7 @@ static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)

 	err = of_iommu_xlate(info->dev, &iommu_spec);
 	of_node_put(iommu_spec.np);
-	if (err)
-		return err;
-
-	return info->np == pdev->bus->dev.of_node;
+	return err;
 }

 const struct iommu_ops *of_iommu_configure(struct device *dev,
-- 
2.13.4.dirty