1. drivers/gpu/drm/sun4i/sun4i_hdmi_audio.o: In function `sun4i_hdmi_audio_startup':
  2. sun4i_hdmi_audio.c:(.text+0x324): undefined reference to `snd_pcm_hw_constraint_eld'
  3. drivers/gpu/drm/sun4i/sun4i_hdmi_audio.o: In function `sun4i_hdmi_audio_create':
  4. sun4i_hdmi_audio.c:(.text+0x3b8): undefined reference to `devm_snd_dmaengine_pcm_register'
  5. sun4i_hdmi_audio.c:(.text+0x3d2): undefined reference to `devm_snd_soc_register_component'
  6. sun4i_hdmi_audio.c:(.text+0x476): undefined reference to `devm_snd_soc_register_card'
  7. drivers/gpu/drm/sun4i/sun4i_hdmi_audio.o: In function `.LANCHOR0':
  8. sun4i_hdmi_audio.c:(.rodata+0x0): undefined reference to `snd_dmaengine_pcm_prepare_slave_config'
  9. Makefile:1078: recipe for target 'vmlinux' failed
  10. make: *** [vmlinux] Error 1

result whe applying patch 'Add-support-for-sun4i-HDMI-audio.patch' on top of 5.5.5 kernel..