Comment 22 for bug 1606078

ubuntu 16.04.2 fresh install
no sound over hdmi

if i boot from linux mint cinnamon 18.1 (live cd) the sound works fine.

Gigabyte BRIX GB-BKI3A-7100 (intel i3 7100u) 16gb ddr4 samsung evo850 m.2 ssd

uname -a
Linux i37100u 4.8.0-41-generic #44~16.04.1-Ubuntu SMP Fri Mar 3 17:11:16 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

lspci
00:00.0 Host bridge: Intel Corporation Device 5904 (rev 02)
00:02.0 VGA compatible controller: Intel Corporation Device 5916 (rev 02)
00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI (rev 21)
00:17.0 SATA controller: Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode] (rev 21)
00:1c.0 PCI bridge: Intel Corporation Device 9d10 (rev f1)
00:1c.5 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port (rev f1)
00:1f.0 ISA bridge: Intel Corporation Device 9d58 (rev 21)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
00:1f.3 Audio device: Intel Corporation Device 9d71 (rev 21)
00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection I219-LM (rev 21)
01:00.0 USB controller: ASMedia Technology Inc. ASM1142 USB 3.1 Host Controller
02:00.0 Network controller: Intel Corporation Device 24fb (rev 10)

sudo aplay -l
**** List of PLAYBACK Hardware Devices ****
Home directory not accessible: Άρνηση πρόσβασης
κάρτα 0: PCH [HDA Intel PCH], συσκευή 0: ALC255 Analog [ALC255 Analog]
  Υποσυσκευές: 1/1
  Υποσυσκευή #0: subdevice #0
κάρτα 0: PCH [HDA Intel PCH], συσκευή 3: HDMI 0 [HDMI 0]
  Υποσυσκευές: 1/1
  Υποσυσκευή #0: subdevice #0
κάρτα 0: PCH [HDA Intel PCH], συσκευή 7: HDMI 1 [HDMI 1]
  Υποσυσκευές: 1/1
  Υποσυσκευή #0: subdevice #0
κάρτα 0: PCH [HDA Intel PCH], συσκευή 8: HDMI 2 [HDMI 2]
  Υποσυσκευές: 1/1
  Υποσυσκευή #0: subdevice #0