On Thu, 2017-07-13 at 06:29 -0500, Bjorn Helgaas wrote:
> > Indeed our host controller depends on ARM64 so maybe it would make
> > sense to move the quirk arch/arm64/kernel/pci.c; however regardless
> > why is it strictly required for a VGA device to be legacy one in order
> > to make it the default boot device?
> > i.e. couldn't we have:
> >
> > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> > index 0f5b2dd..a6b606c 100644
> > --- a/drivers/gpu/vga/vgaarb.c
> > +++ b/drivers/gpu/vga/vgaarb.c
> > @@ -667,8 +667,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
> > /* Deal with VGA default device. Use first enabled one
> > * by default if arch doesn't have it's own hook
> > */
> > - if (vga_default == NULL &&
> > - ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)) {
> > + if (vga_default == NULL) {
> > vgaarb_info(&pdev->dev, "setting as boot VGA device\n");
> > vga_set_default_device(pdev);
> > }
>
> I don't know enough about the VGA arbiter to answer this. This test was
> part of the initial implementation: deb2d2ecd43d ("PCI/GPU: implement VGA
> arbitration on Linux") by Ben.
The above simply uses the first device that has memory and IO enabled
as the default device (you don't need to have a default device).
This is essentially picking up whatever device had been initialized
by the BIOS/firmware as default. This is needed for example on x86
where the BIOS tends to only initialize one device.
I'm not sure what problem you are trying to solve here ?
Cheers,
Ben.
