This bug was fixed in the package linux-firmware - 1.157.6
---------------
linux-firmware (1.157.6) xenial; urgency=medium
* linux-firmware 1.157.5 causes sound issues after initramfs update
(LP: #1645911)
- Revert "linux-firmware: First DMC image for Kabylake."
* Trigger update-initramfs following linux-firmware install (LP: #1646197)
- UBUNTU: Add postinst script to update initrds
-- Seth Forshee <seth.fors...@canonical.com> Wed, 30 Nov 2016 15:05:05
-0600
** Changed in: linux-firmware (Ubuntu Xenial)
Status: Fix Committed => Fix Released
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https://bugs.launchpad.net/bugs/1645911
Title:
linux-firmware 1.157.5 causes sound issues after initramfs update
Status in linux package in Ubuntu:
Fix Released
Status in linux-firmware package in Ubuntu:
Invalid
Status in linux source package in Xenial:
Confirmed
Status in linux-firmware source package in Xenial:
Fix Released
Bug description:
On laptops with Kaby Lake processors and Sunrise point chipsets
(System76 Lemu7), updating to the current (1.157.5) version of the
linux-firmware package and then updating initramfs causes sound
issues. This can manifest in two ways:
1: Volume hotkeys and controls appear to work, but actual playback volume
remains the same.
Three HDMI devices appear in the sound-settings gui, despite no HDMI
device connected (and only 1 HDMI port)
2: 'Dummy Output' is the only device in the sound-settings gui, and there is
no sound output at all.
In both cases dmesg shows error output relating to snd_hda_codec_hdmi.
This bug only affects Xenial, not Yakkety. Xenial still exhibits the
above symptoms after installing the current Yakkety linux-firmware
package.
I believe the issue is related to the Kaby Lake firmware. In testing,
I was able to remove '/lib/firmware/i915/kbl_dmc_ver1_01.bin', run
'sudo update-initramfs -u', and reboot to get sound working correctly
again.
Perhaps this firmware is needed for the upcoming Union Point chipsets,
but causes problems with the for Kaby Lake processor laptops running
the 4.4.0 kernel and Sunrise Point chipsets. There is either a bug in
the new Kaby Lake firmware or it is being erroneously applied to
inappropriate hardware.
I have received a number of reports of users running into this bug,
presumably anyone who updated to the latest kernel and linux-firmware
packages at the same time. Based on testing, next kernel update could
trigger the bug for many more users.
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