after update from kubuntu 15.10 to 16.04 soundcard isn't recognized any longer

[andschuster]

Using Kubuntu 15.10 my sound system works well on my Thinkpad L520. After upgrading to 16.04 the sound device isn't recognized any longer. "aplay -l" reports that there is no sound device. lspci reports for the type of the device:

00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 04)

The following modules are loaded:

lsmod|grep snd
snd_hda_codec_realtek 81920 2
snd_hda_codec_generic 77824 1 snd_hda_codec_realtek
snd_hda_intel 36864 0
snd_hda_codec 135168 3 snd_hda_codec_realtek,snd_hda_codec_generic,snd_hda_intel
snd_hda_core 73728 4 snd_hda_codec_realtek,snd_hda_codec_generic,snd_hda_codec,snd_hda_intel
snd_hwdep 16384 1 snd_hda_codec
snd_pcm 106496 3 snd_hda_codec,snd_hda_intel,snd_hda_core
snd_seq_midi 16384 0
snd_seq_midi_event 16384 1 snd_seq_midi
snd_rawmidi 32768 1 snd_seq_midi
snd_seq 69632 2 snd_seq_midi_event,snd_seq_midi
snd_seq_device 16384 3 snd_seq,snd_rawmidi,snd_seq_midi
snd_timer 32768 2 snd_pcm,snd_seq
snd 81920 10 snd_hda_codec_realtek,snd_hwdep,snd_timer,snd_pcm,snd_seq,snd_rawmidi,snd_hda_codec_generic,snd_hda_codec,snd_hda_intel,snd_seq_device
soundcore 16384 1 snd

lsb_release -rd
Description: Ubuntu 16.04 LTS
Release: 16.04

[Paul White (paulw2u)]

According to https://wiki.ubuntu.com/Bugs/FindRightPackage#When_upgrading_Ubuntu_.28or_derivatives.29, ubuntu-release-upgrader is the package against which bugs should be filed.

[andschuster (andreas-schuster2)]

Some further information: Using dmesg I got:

[ 20.403982] snd_hda_codec_realtek hdaudioC0D0: autoconfig for ALC269VB: line_outs=1 (0x14/0x0/0x0/0x0/0x0) type:speaker
[ 20.403985] snd_hda_codec_realtek hdaudioC0D0: speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
[ 20.403987] snd_hda_codec_realtek hdaudioC0D0: hp_outs=1 (0x21/0x0/0x0/0x0/0x0)
[ 20.403988] snd_hda_codec_realtek hdaudioC0D0: mono: mono_out=0x0
[ 20.403989] snd_hda_codec_realtek hdaudioC0D0: inputs:
[ 20.403991] snd_hda_codec_realtek hdaudioC0D0: Mic=0x18
[ 20.403992] snd_hda_codec_realtek hdaudioC0D0: Internal Mic=0x12
[ 20.406256] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
[ 20.407070] IP: [<ffffffff814a0daf>] acpi_ns_walk_namespace+0x4b/0x193
[ 20.407872] PGD 0
[ 20.408659] Oops: 0000 [#1] SMP
[ 20.409446] Modules linked in: snd_hda_codec_realtek(+) intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp media snd_hda_codec_generic snd_hda_intel snd_hda_codec kvm snd_hda_core snd_hwdep irqbypass snd_pcm crct10dif_pclmul crc32_pclmul iwlwifi aesni_intel rtsx_pci_ms memstick cfg80211 snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer snd gpio_ich aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd joydev input_leds mac_hid serio_raw soundcore shpchp mei_me mei lpc_ich binfmt_misc parport_pc ppdev lp parport autofs4 hid_logitech_hidpp hid_logitech_dj usbhid hid rtsx_pci_sdmmc i915 r8169 video i2c_algo_bit drm_kms_helper psmouse syscopyarea sysfillrect sysimgblt mii ahci fb_sys_fops rtsx_pci libahci drm
[ 20.413182] CPU: 1 PID: 379 Comm: systemd-udevd Not tainted 4.4.0-24-generic #43-Ubuntu
[ 20.414121] Hardware name: LENOVO 78595BG/78595BG, BIOS 8GET36WW (1.13 ) 08/16/2011
[ 20.415063] task: ffff8800359d2940 ti: ffff8801a7bf0000 task.ti: ffff8801a7bf0000
[ 20.416007] RIP: 0010:[<ffffffff814a0daf>] [<ffffffff814a0daf>] acpi_ns_walk_namespace+0x4b/0x193
[ 20.416971] RSP: 0018:ffff8801a7bf39e8 EFLAGS: 00010202
[ 20.417926] RAX: ffff8801a7bf3a58 RBX: 0000000000000001 RCX: 0000000000000001
[ 20.418893] RDX: 00000000ffffffff RSI: 0000000000000000 RDI: 0000000000000006
[ 20.419859] RBP: ffff8801a7bf3a38 R08: ffffffff814a13ac R09: 0000000000000000
[ 20.420830] R10: 0000000000000001 R11: ffff880035864680 R12: 0000000000000001
[ 20.421810] R13: ffff8800bf3a4000 R14: 0000000000000000 R15: 0000000000000000
[ 20.422799] FS: 00007fb5f0a1a8c0(0000) GS:ffff8801af500000(0000) knlGS:0000000000000000
[ 20.423797] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 20.424800] CR2: 0000000000000018 CR3: 00000001a7bb3000 CR4: 00000000000406e0
[ 20.425813] Stack:
[ 20.426812] 0000000000000004 0000000000000000 ffffffff814a13ac 00000001ffffffff
[ 20.427846] 0000000000000006 0000000000000000 0000000000000000 ffff8800bf3a4000
[ 20.428880] ffff8800350ce000 ffffffffc05e56d0 ffff8801a7bf3a80 ffffffff814a12b2
[ 20.429922] Call Trace:
[ 20.430950] [<ffffffff814a13ac>] ? acpi_walk_namespace+0xd0/0xd0
[ 20.432000] [<ffffffff814a12b2>] acpi_get_devices+0x6a/0x94
[ 20.433050] [<ffffffffc05dc350>] ? alc_fixup_disable_aamix+0x20/0x20 [snd_hda_codec_realtek]
[ 20.43411...