Setup: I use reverse PRIME with a primary intel and a secondary nouveau card. I have enabled one output on each of the cards. The reverse PRIME (nouveau) output is set as primary output via xrandr.
Whenever there's a DRI user on the reverse PRIME screen, the following message gets written to my kernel log once for each buffer swap:
[drm:drm_wait_vblank [drm]] *ERROR* Unsupported type value 0x7d, supported mask 0x7400003f
Both DRI2 and DRI3 cause this behaviour. I also see tearing on the nouveau output.
Depending on the exact setup (DRI2/DRI3, different DRI users), I also get slightly different messages:
[drm:drm_wait_vblank [drm]] *ERROR* Unsupported type value 0x15d, supported mask 0x7400003f
[drm:drm_wait_vblank [drm]] *ERROR* Unsupported type value 0x400015d, supported mask 0x7400003f
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
01:00.0 VGA compatible controller: NVIDIA Corporation GF119M [Quadro NVS 4200M] (rev a1)
* xserver 1.17.2
* xf86-video-intel 2.99.917-476-g4e668dd
* xf86-video-nouveau 1.0.11-31-g1ff13a9
I opened a bug report for the kernel first (see https://bugzilla.kernel.org/show_bug.cgi?id=105601 ), but was told that this is a userspace bug.
Same issue here on Fedora 22 with intel (LVDS) + nouveau (ext. monitor):
Bug 1243432 - KDE 5 dual monitor setup with intel+nouveau drivers causes journal to be flooded with errors "[drm:drm_wait_vblank [drm]] *ERROR* Unsupported type value ..."