https://bugs.freedesktop.org/show_bug.cgi?id=99881
--- Comment #2 from Michel Dänzer michel@daenzer.net --- It sounds like you have the environment variable DRI_PRIME=1 set for all applications?
Those dmesg messages are normal when the dedicated GPU is powered up, which takes some time. With runpm enabled, it's powered off automatically when nothing uses it for a while.