I've install Kubuntu 17.04 on Dell Vostro 5568 with encrypted filesystem. The laptop comes with UEFI bios. In order to install nvidia drivers I had to disable secure UEFI boot. After turning laptop off and on again the sound card stopped working. The whole hard drive is on encrypted LVM.

```
$ lspci -v | grep -A7 -i "audio"
00:1f.3 Audio device: Intel Corporation Device 9d71 (rev 21)
        Subsystem: Dell Device 0786
        Flags: bus master, fast devsel, latency 32, IRQ 16
        Memory at d5228000 (64-bit, non-prefetchable) [size=16K]
        Memory at d5200000 (64-bit, non-prefetchable) [size=64K]
        Capabilities: [50] Power Management version 3
        Capabilities: [60] MSI: Enable- Count=1/1 Maskable- 64bit+
        Kernel driver in use: snd_hda_intel

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

```

Currently the only audio output device is "Dummy output". 
Funny enough after suspending laptop to hibernation and waking it up the sound card device appears correctly:

```
$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC3246 Analog [ALC3246 Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

```

I'm a bit suspicious about the combination of encrypted filesystem and UEFI boot that might cause problems with detecting hardware.

```
$ cat /proc/asound/card0/codec* | grep Codec
Codec: Realtek ALC3246
Codec: Intel Kabylake HDMI

```

Alsa manual does not explicitly state that **Realtek ALC3246** card is supported but as the card sometimes works and sometimes there's no sound device at all I'm not sure whether it's still a software issue.

**EDIT**: After reboot the sound card is gone again. I've tried disabling and enabling sound card in BIOS without any success.