Hi Bjorn, Yes, this works:
Tested-by: Daniel Axtens <d...@axtens.net> # arm64, ppc64-qemu-tcg Regards, Daniel > On Fri, Sep 01, 2017 at 05:27:41PM +1000, Daniel Axtens wrote: >> This patch set: >> >> - splits the default display handling out from VGA arbiter, into its >> own file and behind its own Kconfig option (and gives the functions >> better names). >> >> - adds extra detection of default devices. To be nominated, the vga >> arbiter and platform hooks must not have nominated a default. A >> card will then only be nominated if it has a driver attached and >> has IO or memory decoding enabled. >> >> - adds relevant documentation. >> >> The practical impact of this is improved X autoconfiguration on some >> arm64 systems. > > I think I gave you bad advice about trying to separate the "default > device" idea from the VGA arbiter. > > It is true that the "VGA arbiter" per se is related to routing the > legacy VGA resources, and the arbiter currently only selects a default > device if it finds a device to which those resources are routed. > > We have some cases where we want to select a default device that may > not support the legacy VGA resources, or where they might not be > routed to the device: > > - systems where we match the EFI framebuffer address with a BAR, and > select that device as default, > > - powerpc systems where there may be no host bridge window that maps > to the legacy VGA resources, > > - your ARM64 systems where the default device may be behind a bridge > that doesn't support legacy VGA routing (PCI_BRIDGE_CTL_VGA) > > But I think trying to split the "default device" part out from the VGA > arbiter ends up being overkill and making things more complicated > instead of simpler. > > Would something like the following work for you as well as the powerpc > case? On powerpc, we already use vga_set_default_device() to select a > device that doesn't use legacy VGA resources, so maybe we can just do > the same on ARM64? > > I suppose there might be wrinkles in how the arbiter deals with > multiple graphics devices on those systems, since I don't think it > identifies these devices that don't use the legacy resources, but it > seems like we live with whatever those on are powerpc and probably can > on ARM64 as well. > > > diff --git a/arch/powerpc/kernel/pci-common.c > b/arch/powerpc/kernel/pci-common.c > index 02831a396419..0ac7aa346c69 100644 > --- a/arch/powerpc/kernel/pci-common.c > +++ b/arch/powerpc/kernel/pci-common.c > @@ -1740,15 +1740,3 @@ static void fixup_hide_host_resource_fsl(struct > pci_dev *dev) > } > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_MOTOROLA, PCI_ANY_ID, > fixup_hide_host_resource_fsl); > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_FREESCALE, PCI_ANY_ID, > fixup_hide_host_resource_fsl); > - > -static void fixup_vga(struct pci_dev *pdev) > -{ > - u16 cmd; > - > - pci_read_config_word(pdev, PCI_COMMAND, &cmd); > - if ((cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) || > !vga_default_device()) > - vga_set_default_device(pdev); > - > -} > -DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_ANY_ID, PCI_ANY_ID, > - PCI_CLASS_DISPLAY_VGA, 8, fixup_vga); > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c > index 76875f6299b8..9df4802c5f04 100644 > --- a/drivers/gpu/vga/vgaarb.c > +++ b/drivers/gpu/vga/vgaarb.c > @@ -1468,6 +1468,21 @@ static int __init vga_arb_device_init(void) > vgaarb_info(dev, "no bridge control possible\n"); > } > > + if (!vga_default_device()) { > + list_for_each_entry(vgadev, &vga_list, list) { > + struct device *dev = &vgadev->pdev->dev; > + u16 cmd; > + > + pdev = vgadev->pdev; > + pci_read_config_word(pdev, PCI_COMMAND, &cmd); > + if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) { > + vgaarb_info(dev, "setting as boot device\n"); > + vga_set_default_device(pdev); > + break; > + } > + } > + } > + > pr_info("loaded\n"); > return rc; > }