Stable team, please backport these two commits to v6.1:
2bd0db4b3f0b ("drm/i915: Allow panel fixed modes to have differing sync polarities") 55cfeecc2197 ("drm/i915: Allow alternate fixed modes always for eDP")
Reference for posterity: https://gitlab.freedesktop.org/drm/intel/-/issues/7841
Thanks, Jani.