Kernel patch to vgaarb.c to add 3D controller detection on Optimus notebooks

vgaarb.c.patch

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index 111d956..bd9a01f 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -507,9 +507,11 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
        struct pci_bus *bus;
        struct pci_dev *bridge;
        u16 cmd;
+       int pci_class = pdev->class >> 8;
 
        /* Only deal with VGA class devices */
-       if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
+       if (pci_class != PCI_CLASS_DISPLAY_VGA &&
+               pci_class != PCI_CLASS_DISPLAY_3D)
                return false;
 
        /* Allocate structure */

Useful in Hybrid graphics use-cases where:

1. GPU offloading via PRIME is used.
2. Where the IGP has all outputs connected to the displays (Integrated eDP or via LVDS) and the dGPU has no direct link to the GPUs.
3. Where the dGPU has some ( and not all!) connectors wired to actual displays. Common in Nvidia Optimus setups that deploy Quadro Mobile GPUs in select SKUs.