Please read this first before considering making a comment:
The root cause of the scope of this bug report was caused by a BIOS error in BIOS A01 that put the sound in an undefined mode that wasn't really I2S and wasn't really HDA. This has been fixed by BIOS A02 ( or later ).
There was an _REV patch that was proposed but not merged upstream. If that (or something similar to it) does get merged upstream, then with BIOS A02+ the audio will operate in I2S mode.
If you have a problem with your computer, please do not make comments here, as this bug report is considered closed. Instead file a new report following https://wiki.ubuntu.com/ReportingBugs . Your issue will not be dealt with by making comments in this report, and will likely be completely ignored.
(This is a public bug report for LP1402828.)
This system has a dual-mode audio with an HDA and an I2S interface. Which shows up depends on the reported _OSI from the last cold boot. Since the kernels in Ubuntu 14.10/15.04 (15.04 uses 3.18 currently) report an _OSI of "Windows 2013", I2S mode is used for audio.
A workaround is to pass acpi_os="!Windows 2013" as a kernel parameter, but this is non-optimal since the mode of the touchpad is affected. It also results in an alternate, less used and tested path in the firmware to be used.
See the attached dmesg log for details on where the failure happens. Notably,
$ dmesg -t | egrep "(audio|snd|INT3438)"
dmar: ACPI device "INT3438:00" under DMAR at fed91000 as 00:13.0
snd_hda_intel 0000:00:03.0: enabling device (0000 -> 0002)
snd_hda_intel 0000:00:03.0: irq 50 for MSI/MSI-X
haswell-pcm-audio haswell-pcm-audio: error: ADSP boot timeout
broadwell-audio broadwell-audio: ASoC: CPU DAI System Pin not registered
platform broadwell-audio: Driver broadwell-audio requests probe deferral
There's also a failure to load the codec firmware after a suspend/resume.
DistroRelease: Ubuntu 15.04
Package: linux-image-3.18.0-9-generic 3.18.0-9.10
ProcVersionSignature: Ubuntu 3.18.0-9.10-generic 3.18.2
Uname: Linux 3.18.0-9-generic x86_64
USER PID ACCESS COMMAND
/dev/snd/controlC0: jared 2139 F.... pulseaudio
Date: Wed Jan 21 20:47:40 2015
InstallationDate: Installed on 2014-11-03 (80 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 0c45:670c Microdia
Bus 001 Device 003: ID 04f3:2051 Elan Microelectronics Corp.
Bus 001 Device 002: ID 8087:0a2a Intel Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Dell Inc. XPS 13 9343
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.18.0-9-generic root=/dev/mapper/ubuntu--vg-root ro video.use_native_backlight=1 video.use_native_backlight=1
UpgradeStatus: Upgraded to vivid on 2015-01-08 (14 days ago)
dmi.bios.vendor: Dell Inc.
dmi.board.vendor: Dell Inc.
dmi.chassis.vendor: Dell Inc.
dmi.product.name: XPS 13 9343
dmi.sys.vendor: Dell Inc.