Hi all,
Previously I posted a patch that provided a quirk for a hibmc card
behind a particular Huawei bridge that allowed it to be marked as the
default device in the VGA arbiter.[0] This lead to some discussion.[1]
It was broadly suggested that a more generic solution would be better,
something in the style of powerpc's fixup_vga() quirk.
Here is my suggested solution:
- Create a Kconfig option ARCH_WANT_VGA_ARB_FALLBACK
- if an arch selects that option, install PCI_FIXUP_CLASS_ENABLE
hook. This hook fires when a card is enabled, which will require
that a driver has been bound.
- if there is no default device when the hook fires, and the device
can control memory and I/O, mark it as default.
The patches are as follows:
(1) powerpc: simplify and fix VGA default device behaviour
This cleans up some quirks in the powerpc implementation of the
vga_fixup. It should make the behaviour match the original
intention.
(2) vgaarb: allow non-legacy cards to be marked as default
Add the Kconfig option, and create the fixup in vgaarb.c gated
behind the option. Nothing happens at this stage because no arch
has selected the option yet.
(3) powerpc: replace vga_fixup() with generic code
Select the option on powerpc and remove the old code. The only
change is that it moves from being a final fixup to an enable
fixup.
(4) arm64: allow non-legacy VGA devices to be default
Select the option on arm64. This solves my problem with the D05,
but may cause other cards to be marked as default on other
boards. This shouldn't cause any real issues but is worth being
aware of.
Regards,
Daniel
[0]: https://patchwork.ozlabs.org/patch/787003/
[1]: https://www.spinics.net/lists/arm-kernel/msg593656.html
Daniel Axtens (4):
powerpc: simplify and fix VGA default device behaviour
vgaarb: allow non-legacy cards to be marked as default
powerpc: replace vga_fixup() with generic code
arm64: allow non-legacy VGA devices to be default
arch/arm64/Kconfig | 1 +
arch/powerpc/Kconfig | 1 +
arch/powerpc/kernel/pci-common.c | 12 ------------
drivers/gpu/vga/Kconfig | 7 +++++++
drivers/gpu/vga/vgaarb.c | 21 +++++++++++++++++++++
5 files changed, 30 insertions(+), 12 deletions(-)
--
2.11.0
