Further on this bug only manifests on the ATI/AMD side. NVIDIA cards do not
seem to have a problem with this new PCIe feature activated in commit
60db3a4d8cc9073cf56264785197ba75ee1caca4.

On the same system Xorg is running with an EXA accelerated desktop on a Nvidia
GeForce 6600 (NV43), card detection is fine:

[   10.818686] nouveau 0000:0a:00.0: DRM: VRAM: 252 MiB
[   10.818691] nouveau 0000:0a:00.0: DRM: GART: 512 MiB
[   10.818724] nouveau 0000:0a:00.0: DRM: TMDS table version 1.1
[   10.818729] nouveau 0000:0a:00.0: DRM: DCB version 3.0
[   10.818735] nouveau 0000:0a:00.0: DRM: DCB outp 00: 01000100 00000028
[   10.818739] nouveau 0000:0a:00.0: DRM: DCB outp 01: 03000102 00000000
[   10.818744] nouveau 0000:0a:00.0: DRM: DCB outp 02: 04011210 00000028
[   10.818749] nouveau 0000:0a:00.0: DRM: DCB outp 03: 02111212 02000100
[   10.818753] nouveau 0000:0a:00.0: DRM: DCB outp 04: 02011211 0020c070
[   10.818758] nouveau 0000:0a:00.0: DRM: DCB conn 00: 1030
[   10.818762] nouveau 0000:0a:00.0: DRM: DCB conn 01: 2130
[   10.826071] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[   10.826081] [drm] Driver supports precise vblank timestamp query.
[   10.829953] nouveau 0000:0a:00.0: DRM: MM: using M2MF for buffer copies
[   10.830013] nouveau 0000:0a:00.0: DRM: Setting dpms mode 3 on TV encoder
(output 4)
[   10.937421] nouveau 0000:0a:00.0: DRM: allocated 1920x1080 fb: 0x9000, bo
c00000045949e800
[   11.069093] nouveau 0000:0a:00.0: DRM: 0x14C5: Parsing digital output script
table
[   11.229337] [drm] Initialized nouveau 1.3.1 20120801 for 0000:0a:00.0 on
minor 0

[    52.472] (--) Depth 24 pixmap format is 32 bpp
[    52.478] (II) NOUVEAU(0): Channel setup complete.
[    52.490] (II) NOUVEAU(0): Hardware support for Present enabled
[    52.490] (II) NOUVEAU(0): [DRI2] Setup complete
[    52.490] (II) NOUVEAU(0): [DRI2]   DRI driver: nouveau
[    52.490] (II) NOUVEAU(0): [DRI2]   VDPAU driver: nouveau
[    52.490] (II) Loading sub module "exa"
[    52.490] (II) LoadModule: "exa"
[    52.491] (II) Loading /usr/lib64/xorg/modules/libexa.so
[    52.493] (II) Module exa: vendor="X.Org Foundation"
[    52.493]    compiled for 1.19.4, module version = 2.6.0
[    52.493]    ABI class: X.Org Video Driver, version 23.0
[    52.493] (II) EXA(0): Driver allocated offscreen pixmaps
[    52.493] (II) EXA(0): Driver registered support for the following
operations:
[    52.493] (II)         Solid
[    52.493] (II)         Copy
[    52.493] (II)         Composite (RENDER acceleration)
[    52.493] (II)         UploadToScreen
[    52.493] (II)         DownloadFromScreen
[    52.493] (==) NOUVEAU(0): Backing store enabled
[    52.493] (==) NOUVEAU(0): Silken mouse enabled
[    52.494] (II) NOUVEAU(0): [XvMC] Associated with NV40 texture adapter.
[    52.494] (II) NOUVEAU(0): [XvMC] Extension initialized.
[    52.494] (==) NOUVEAU(0): DPMS enabled
[    52.495] (II) NOUVEAU(0): RandR 1.2 enabled, ignore the following RandR
disabled message.
[    52.497] (--) RandR disabled