[+to Maarten, Maxime, Thomas: sorry, I forgot to use get_maintainer.pl so I missed you the first time. Beginning of thread: https://lore.kernel.org/all/20220106000658.243509-1-helgaas@xxxxxxxxxx/#t Git branch with this v8 + a couple trivial renames, based on v5.16-rc1: https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/log/?h=0f4caffa1297] On Wed, Jan 05, 2022 at 06:06:48PM -0600, Bjorn Helgaas wrote: > From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > Current default VGA device selection fails in some cases because part of it > is done in the vga_arb_device_init() subsys_initcall, and some arches > enumerate PCI devices in pcibios_init(), which runs *after* that. > > For example: > > - On BMC system, the AST2500 bridge [1a03:1150] does not implement > PCI_BRIDGE_CTL_VGA. This is perfectly legal but means the legacy VGA > resources won't reach downstream devices unless they're included in the > usual bridge windows. > > - vga_arb_select_default_device() will set a device below such a bridge > as the default VGA device as long as it has PCI_COMMAND_IO and > PCI_COMMAND_MEMORY enabled. > > - vga_arbiter_add_pci_device() is called for every VGA device, either at > boot-time or at hot-add time, and it will also set the device as the > default VGA device, but ONLY if all bridges leading to it implement > PCI_BRIDGE_CTL_VGA. > > - This difference between vga_arb_select_default_device() and > vga_arbiter_add_pci_device() means that a device below an AST2500 or > similar bridge can only be set as the default if it is enumerated > before vga_arb_device_init(). > > - On ACPI-based systems, PCI devices are enumerated by acpi_init(), which > runs before vga_arb_device_init(). > > - On non-ACPI systems, like on MIPS system, they are enumerated by > pcibios_init(), which typically runs *after* vga_arb_device_init(). > > This series consolidates all the default VGA device selection in > vga_arbiter_add_pci_device(), which is always called after enumerating a > PCI device. > > Almost all the work here is Huacai's. I restructured it a little bit and > added a few trivial patches on top. > > I'd like to move vgaarb.c to drivers/pci eventually, but there's another > initcall ordering snag that needs to be resolved first, so this leaves > it where it is. > > Bjorn > > Version history: > V0 original implementation as final quirk to set default device. > https://lore.kernel.org/r/20210514080025.1828197-6-chenhuacai@xxxxxxxxxxx > > V1 rework vgaarb to do all default device selection in > vga_arbiter_add_pci_device(). > https://lore.kernel.org/r/20210705100503.1120643-1-chenhuacai@xxxxxxxxxxx > > V2 move arbiter to PCI subsystem, fix nits. > https://lore.kernel.org/r/20210722212920.347118-1-helgaas@xxxxxxxxxx > > V3 rewrite the commit log of the last patch (which is also summarized > by Bjorn). > https://lore.kernel.org/r/20210820100832.663931-1-chenhuacai@xxxxxxxxxxx > > V4 split the last patch to two steps. > https://lore.kernel.org/r/20210827083129.2781420-1-chenhuacai@xxxxxxxxxxx > > V5 split Patch-9 again and sort the patches. > https://lore.kernel.org/r/20210911093056.1555274-1-chenhuacai@xxxxxxxxxxx > > V6 split Patch-5 again and sort the patches again. > https://lore.kernel.org/r/20210916082941.3421838-1-chenhuacai@xxxxxxxxxxx > > V7 stop moving vgaarb to drivers/pci because of ordering issues with > misc_init(). > https://lore.kernel.org/r/20211015061512.2941859-1-chenhuacai@xxxxxxxxxxx > https://lore.kernel.org/r/CAAhV-H7FhAjM-Ha42Z1dLrE4PvC9frfyeU27KHWcyWKkMftEsA@xxxxxxxxxxxxxx > > > Bjorn Helgaas (8): > vgaarb: Factor out vga_select_framebuffer_device() > vgaarb: Factor out default VGA device selection > vgaarb: Move framebuffer detection to ADD_DEVICE path > vgaarb: Move non-legacy VGA detection to ADD_DEVICE path > vgaarb: Move disabled VGA device detection to ADD_DEVICE path > vgaarb: Remove empty vga_arb_device_card_gone() > vgaarb: Use unsigned format string to print lock counts > vgaarb: Replace full MIT license text with SPDX identifier > > Huacai Chen (2): > vgaarb: Move vga_arb_integrated_gpu() earlier in file > vgaarb: Log bridge control messages when adding devices > > drivers/gpu/vga/vgaarb.c | 311 +++++++++++++++++++-------------------- > 1 file changed, 154 insertions(+), 157 deletions(-) > > -- > 2.25.1 > >
