Regression: drm: Lobotomize set_busid nonsense for !pci drivers (a325725633c2)

[Laszlo Ersek]

On 09/30/16 12:35, Hans de Goede wrote:

> Attached are 2 patches against the xserver which should fix this,
> please give them a try.

Sorry about the delay.

The patches don't seem to fix the issue for me. Please see the Xorg log
attached.

I tested the patches as follows. Given that my bisection had been done
in a Fedora 24 guest, using

  xorg-x11-server-1.18.4-4.fc24
  http://koji.fedoraproject.org/koji/buildinfo?buildID=794494

I now rebuilt the guest kernel exactly at the failing commit (a325725
"drm: Lobotomize set_busid nonsense for !pci drivers"), and first
reproduced the issue with the above X server.

Then, I ported your patches to "xorg-server-1.18.4" (using the upstream
xserver tree), and rebuilt the Fedora package with the backport. For the
backport, I had to cherry-pick the following two patches from master first:

1 ca8d88e50310 xfree86: recognize primary BUS_PCI device in
               xf86IsPrimaryPlatform()
2 ea91db4b8331 config: fix GPUDevice fail when AutoAddGPU off + BusID

This way your patches applied cleanly. (Cherry pick #1 above is actually
necessary for semantics, while cherry pick #2 is needed for a clean
context only, and has no impact for this test.)

That is, in total, I added the following four patches to the Fedora 24
package:

1 xfree86: recognize primary BUS_PCI device in xf86IsPrimaryPlatform()
2 config: fix GPUDevice fail when AutoAddGPU off + BusID
3 xfree86: Make adding unclaimed devices as GPU devices a separate step
4 xfree86: Try harder to find atleast 1 non GPU Screen

You can find the scratch build that I used for testing here:

  xorg-x11-server-1.18.4-4.hans_bz1366842_2.fc24
  http://koji.fedoraproject.org/koji/taskinfo?taskID=15875087

Another reason I used F24's X server as basis, rather than upstream
HEAD, is that Fedora 24 is pretty young, and it's already on kernel
4.7.4, and I believe it will soon move to kernel 4.8, without
(necessarily) rebasing its X server package to upstream. IOW the kernel
upgrade to 4.8 will break X in Fedora 24 too, and then I expect the
Fedora X maintainers would have to cherry pick those two patches as
dependencies just the same.

To summarize, the patches don't seem to help. I shall nonetheless thank
you for spending your Friday on this!

Laszlo
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