Intel HD Audio clicks when a laptop is running on battery power

Yet another audio problem in Linux on my laptop. There were clicks in the audio output from headphones and the built-in speakers while running the laptop on battery power and listening to music. Details of my laptop’s two sound cards are given below:

# lspci | grep -i audio
00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset High Definition Audio (rev 05)
01:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Redwood HDMI Audio [Radeon HD 5000 Series]

# hwinfo --sound
17: PCI 1b.0: 0403 Audio device
[Created at pci.328]
Unique ID: u1Nb.sEm8vDosIQF
SysFS ID: /devices/pci0000:00/0000:00:1b.0
SysFS BusID: 0000:00:1b.0
Hardware Class: sound
Model: "Intel 5 Series/3400 Series Chipset High Definition Audio"
Vendor: pci 0x8086 "Intel Corporation"
Device: pci 0x3b56 "5 Series/3400 Series Chipset High Definition Audio"
SubVendor: pci 0x14c0 "COMPAL Electronics Inc"
SubDevice: pci 0x0043
Revision: 0x05
Driver: "snd_hda_intel"
Driver Modules: "snd_hda_intel"
Memory Range: 0xd8100000-0xd8103fff (rw,non-prefetchable)
IRQ: 31 (17929 events)
Module Alias: "pci:v00008086d00003B56sv000014C0sd00000043bc04sc03i00"
Driver Info #0:
Driver Status: snd_hda_intel is active
Driver Activation Cmd: "modprobe snd_hda_intel"
Config Status: cfg=new, avail=yes, need=no, active=unknown

28: PCI 100.1: 0403 Audio device
[Created at pci.328]
Unique ID: NXNs.nzRufOXHPI0
Parent ID: 3hqH.Db2_i3v_bw2
SysFS ID: /devices/pci0000:00/0000:00:03.0/0000:01:00.1
SysFS BusID: 0000:01:00.1
Hardware Class: sound
Model: "ATI Redwood HDMI Audio [Radeon HD 5000 Series]"
Vendor: pci 0x1002 "ATI Technologies Inc"
Device: pci 0xaa60 "Redwood HDMI Audio [Radeon HD 5000 Series]"
SubVendor: pci 0x0000
SubDevice: pci 0xaa60
Driver: "snd_hda_intel"
Driver Modules: "snd_hda_intel"
Memory Range: 0xd8020000-0xd8023fff (rw,non-prefetchable)
IRQ: 32 (87 events)
Module Alias: "pci:v00001002d0000AA60sv00000000sd0000AA60bc04sc03i00"
Driver Info #0:
Driver Status: snd_hda_intel is active
Driver Activation Cmd: "modprobe snd_hda_intel"
Config Status: cfg=new, avail=yes, need=no, active=unknown
Attached to: #9 (PCI bridge)

The audio codecs in use are as follows:

# cat /proc/asound/card0/codec* | grep Codec
Codec: Realtek ALC272
# cat /proc/asound/card1/codec* | grep Codec
Codec: ATI R6xx HDMI

The kernel modules loaded are as follows:

# lsmod | grep codec
snd_hda_codec_realtek 50367 1
snd_hda_codec_hdmi 32069 1
snd_hda_codec_generic 40974 1 snd_hda_codec_realtek
snd_hda_codec 76106 5 snd_hda_codec_realtek,snd_hda_codec_hdmi,snd_hda_codec_generic,snd_hda_int
el,snd_hda_controller
snd_hwdep 5373 1 snd_hda_codec
snd_pcm 67896 4 snd_hda_codec_hdmi,snd_hda_codec,snd_hda_i
ntel,snd_hda_controller
snd 49659 16 snd_hda_codec_realtek,snd_hwdep,snd_timer,snd_hda_codec_hdmi,snd_pcm,snd_h
da_codec_generic,snd_hda_codec,snd_hda_intel

The Linux kernel has a power-saving feature for Intel HD Audio cards. Each time the audio card goes into the power-saving state, or wakes up from the power-saving state when playing audio, it may produce a clicking noise. Kernel parameter CONFIG_SND_HDA_POWER_SAVE_DEFAULT is used to specify the default time-out in seconds, and setting it to zero disables power-saving mode. Similarly, kernel parameter CONFIG_SND_AC97_POWER_SAVE_DEFAULT is used to specify the default time-out in seconds for AC97 power-saving mode, and setting it to zero disables AC97 power-saving mode. As you can see below, I have both of those parameters set to zero in the kernel:

# grep POWER_SAVE /usr/src/linux/.config
CONFIG_SND_AC97_POWER_SAVE=y
CONFIG_SND_AC97_POWER_SAVE_DEFAULT=0
CONFIG_SND_HDA_POWER_SAVE_DEFAULT=0

Yet I still heard clicks when the laptop was running under battery power. To disable the HD Audio power-save mode for good, I added ‘snd_hda_intel.power_save=0‘ to the end of the kernel boot line in /etc/default/grub and regenerated the grub.cfg file:

# grep GRUB_CMDLINE_LINUX /etc/default/grub
GRUB_CMDLINE_LINUX="BOOT_IMAGE=/kernel-genkernel-x86_64-3.17.1-gentoo-r1 root=/dev/ram0 ramdisk=8192 real_root=/dev/sda6 init=/linuxrc splash=silent,theme:Emergance console=tty1 quiet resume=swap:/dev/sda5 real_resume=/dev/sda5 intel_iommu=off net.ifnames=0 snd_hda_intel.power_save=0"

# mount /dev/sda3 /boot # My boot directory is on its own partition.
# grub2-mkconfig -o /boot/grub/grub.cfg

After rebooting, there are no more clicks when listening to audio under battery power. Problem solved.

About Fitzcarraldo
A Linux user with an interest in all things technical.

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