On Tue, Jul 28, 2020 at 10:17:19PM -0500, Daniel Dadap wrote:
> On 7/27/20 7:11 PM, Barnabás P??cze wrote:
> > > + while ((dev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, dev))) {
> > > + switch (dev->vendor) {
> > > + case 0x8086:
> > > + pci_dev_put(ig_dev);
> > > + ig_dev = pci_dev_get(dev);
> > > + break;
> > > + case 0x10de:
> > > + pci_dev_put(dg_dev);
> > > + dg_dev = pci_dev_get(dev);
> > > + break;
> > > + default:
> > > + break;
> > > + }
> > > + }
> > > +
> >
> > Regardless of how improbable, I am wondering what happens if an
> > external GPU is connected to a dual-GPU laptop? Cannot that
> > interfere with this device lookup logic?
>
> I don't think it'll be a problem, since an external GPU won't have an
> implementation of the MXDM/MXDS methods in its associated ACPI node, so even
> if the eGPU is plugged in at the time this module loads, it should fail to
> initialize unless there is also an internal discrete GPU which does support
> MXDM/MXDS.
Still, dg_dev may point to the wrong device. You can avoid it by
adding the following at the top of the while loop:
if (pci_is_thunderbolt_attached(dev))
continue;
Thanks,
Lukas
