Comment # 14 on bug 1095265 from Takashi Iwai

OK, then it implies that the detection of the output right after boot doesn't
work properly.

Could you boot with drm.debug=0x0e and get the dmesg output?
Also, after that, turn off/on the TV to get the output working, and get dmesg
output again.  Please upload both to Bugzilla.

Last but not least, it'd be great if you can test OBS Kernel:stable kernel to
see whether the issue appears or not.