[PATCH] drm: fixed access to PCI host bridges

[Lucas Kannebley Tavares <lucaskt@linux.vnet.ibm.com>]

During the process of obtaining the speed cap for the device, it
attempts go get the PCI Host bus. However on architectures such as PPC
or IA64, those do not appear as devices.

Signed-off-by: Lucas Kannebley Tavares <lucaskt@linux.vnet.ibm.com>
---
  drivers/gpu/drm/drm_pci.c |    5 +++++
  1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
index 754bc96..ea41234 100644
--- a/drivers/gpu/drm/drm_pci.c
+++ b/drivers/gpu/drm/drm_pci.c
@@ -479,8 +479,13 @@ int drm_pcie_get_speed_cap_mask(struct drm_device 
*dev, u32 *mask)
  	if (!pci_is_pcie(dev->pdev))
  		return -EINVAL;

+	// find PCI device for capabilities
  	root = dev->pdev->bus->self;

+	// some architectures might not have host bridges as PCI devices
+	if (root == NULL)
+		root = dev->pdev;
+
  	pos = pci_pcie_cap(root);
  	if (!pos)
  		return -EINVAL;

-- 
Lucas Kannebley Tavares
Software Engineer
IBM Linux Technology Center