From: Dave Airlie airlied@redhat.com

I assumed all PCI buses had a bridge, but playing with qemu recently, I discovered vgaarb bug where it wasn't detecting both devices shared a bridge at the root level.

Don't check for NULL, if two buses have a NULL bridge, assume the share the root bus.

Signed-off-by: Dave Airlie airlied@redhat.com --- drivers/gpu/vga/vgaarb.c | 44 +++++++++++++++++++++----------------------- 1 files changed, 21 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c index c72f1c0..bdde899 100644 --- a/drivers/gpu/vga/vgaarb.c +++ b/drivers/gpu/vga/vgaarb.c @@ -465,31 +465,29 @@ static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev) while (new_bus) { new_bridge = new_bus->self;

- if (new_bridge) { - /* go through list of devices already registered */ - list_for_each_entry(same_bridge_vgadev, &vga_list, list) { - bus = same_bridge_vgadev->pdev->bus; - bridge = bus->self; - - /* see if the share a bridge with this device */ - if (new_bridge == bridge) { - /* if their direct parent bridge is the same - as any bridge of this device then it can't be used - for that device */ - same_bridge_vgadev->bridge_has_one_vga = false; - } + /* go through list of devices already registered */ + list_for_each_entry(same_bridge_vgadev, &vga_list, list) { + bus = same_bridge_vgadev->pdev->bus; + bridge = bus->self; + + /* see if the share a bridge with this device */ + if (new_bridge == bridge) { + /* if their direct parent bridge is the same + as any bridge of this device then it can't be used + for that device */ + same_bridge_vgadev->bridge_has_one_vga = false; + }

- /* now iterate the previous devices bridge hierarchy */ - /* if the new devices parent bridge is in the other devices - hierarchy then we can't use it to control this device */ - while (bus) { - bridge = bus->self; - if (bridge) { - if (bridge == vgadev->pdev->bus->self) - vgadev->bridge_has_one_vga = false; - } - bus = bus->parent; + /* now iterate the previous devices bridge hierarchy */ + /* if the new devices parent bridge is in the other devices + hierarchy then we can't use it to control this device */ + while (bus) { + bridge = bus->self; + if (bridge) { + if (bridge == vgadev->pdev->bus->self) + vgadev->bridge_has_one_vga = false; } + bus = bus->parent; } } new_bus = new_bus->parent;