[PATCH] pci: of : fix BUG: unable to handle kernel

[Murali Karicheri <m-karicheri2@ti.com>]

On some platforms such as that based on x86, ia64 etc, root bus is
created with parent node passed in as NULL to pci_create_root_bus().
On these platforms, the patch series "PCI: get DMA configuration from
parent device" when applied causes kernel crash. So add a check for this
in of_pci_dma_configure()

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
---
 drivers/of/of_pci.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 86d3c38..a8e485c 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -129,6 +129,10 @@ void of_pci_dma_configure(struct pci_dev *pci_dev)
 	struct device *dev = &pci_dev->dev;
 	struct device *bridge = pci_get_host_bridge_device(pci_dev);
 
+	/* Some platforms can have bridge->parent set to NULL */
+	if (!bridge->parent)
+		return;
+
 	of_dma_configure(dev, bridge->parent->of_node);
 	pci_put_host_bridge_device(bridge);
 }
-- 
1.7.9.5