Upstream problem with OMAP MMC seems to be solved.
So I have a Letux kernel tree: http://git.goldelico.com/?p=gta04-kernel.git;a=shortlog;h=refs/heads/4.3-rc4
And a omapdrm version: http://git.goldelico.com/?p=gta04-kernel.git;a=shortlog;h=refs/heads/work/hn...
omap_crtc_atomic_flush still there, but X-event-queue overflow appears to be gone away!
BR, Nikolaus