On beagle-x15 I see these errors after modprobe:
DSS: OMAP DSS rev 6.1
omapdss_dss 58000000.dss: bound 58001000.dispc (ops dispc_component_ops [omapdss])
omapdss_dss 58000000.dss: bound 58040000.encoder (ops hdmi5_component_ops [omapdss])
[drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
omapdrm omapdrm.0: [drm] Cannot find any crtc or sizes
[drm] Initialized omapdrm 1.0.0 20110917 for omapdrm.0 on minor 0
omapdrm omapdrm.0: [drm] Cannot find any crtc or sizes
aic_dvdd_fixed: disabling
ldousb: disabling
Maybe I'm missing some related module on x15?
Still did not figure what I might be missing on x15 :)