On 01/09/17 17:27, Daniel Axtens wrote:
The VGA arbiter selects a default VGA device that is enabled and
reachable via the legacy VGA resources (mem 0xa0000-0xbffff, io
0x3b0-0x3bb, io 0x3c0-0x3df, etc).
(As a special case for x86 and IA64, this can be overridden by
EFI.)
If there is no such device, e.g., because there's no enabled VGA
device, the host bridge doesn't support access to those legacy
resources, or a PCI-PCI bridge doesn't have VGA Enable set, a
platform may select an arbitrary device by calling
pci_set_default_display(). powerpc does this, for example.
If there is also no platform hook, there will be no default
device nominated. This is not necessarily what we want.
Add handling for devices that aren't handled by the vga arbiter or
platform by adding a late initcall and a class enable hook. If there
is no default from vgaarb or the platform then the first VGA card
that is enabled, has a driver bound, and can decode memory or I/O
will be marked as default.
This means single-card setups on systems without access to legacy
areas and without arch hooks will work. Multi-card setups on these
systems will nominate an arbitrary device, rather than no devices.
Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx>
---
v3:
Split out from re-organisation for simplicity.
Add better description and better documentaion.
Thanks to (in no particular order), Daniel Vetter, Lorenzo Pieralisi,
Ard Biesheuvel and Dave Airlie. Special thanks to Ben Herrenschmidt
and Bjorn Helgass, whose prose I have borrowed.
v1:
Tested on:
- x86_64 laptop
- arm64 D05 board with hibmc card
- qemu powerpc with tcg and bochs std-vga
I know this adds another config option and that's a bit sad, but
we can't include it unconditionally as it depends on PCI.
Suggestions welcome.
Tested on our iMac G5, the fallback handler doesn't fire (which should
be correct).
Tested-by: Andrew Donnellan <andrew.donnellan@xxxxxxxxxxx>
+static void vga_default_enable_hook(struct pci_dev *pdev)
+{
+ if (!vga_default_active)
+ return;
+
+ if (pci_default_display())
+ return;
+
+ vga_default_try_device(pdev);
+}
+DECLARE_PCI_FIXUP_CLASS_ENABLE(PCI_ANY_ID, PCI_ANY_ID,
+ PCI_CLASS_DISPLAY_VGA, 8,
+ vga_default_enable_hook)
Looks like you have some spaces/tabs inconsistencies here.
--
Andrew Donnellan OzLabs, ADL Canberra
andrew.donnellan@xxxxxxxxxxx IBM Australia Limited
