[coreboot] Investigating the high pitched noise on the x60 tablet
Charles Devereaux
coreboot at guylhem.net
Sun Jun 29 19:40:23 CEST 2014
Hello
On Mon, Jun 9, 2014 at 5:56 PM, Peter Stuge <peter at stuge.se> wrote:
>
> The noise is created by switching between states.
>
> I expect that the noise comes from power supply circuitry.
>
> Use an oscilloscope in clever ways to find the source.
>
I don't have an oscilloscope, however I created the following script
following glugglug suggestion - it fixes the noise (and also add some
battery life) : http://pastebin.ca/2816554
## reduce sound power consumption (only works while everything is muted)
amixer set Master mute nocap
amixer set CD mute nocap
amixer set Mic mute nocap
echo 'Y' > /sys/module/snd_hda_intel/parameters/power_save_controller
echo '1' > /sys/module/snd_hda_intel/parameters/power_save
## reduce SATA power consumption
for i in /sys/class/scsi_host/host*/link_power_management_policy; do echo
'min_
power' > $i; done
## reduce USB power consumption with autosuspend
for i in /sys/bus/usb/devices/*/power/autosuspend; do echo '1' > $i; done
for i in /sys/bus/usb/devices/*/power/control; do echo 'auto' > $i; done
## other powertop recommanded settings
echo '0' > '/proc/sys/kernel/nmi_watchdog'
# 15 seconds by default, use 60 instead
echo '6000' > '/proc/sys/vm/dirty_writeback_centisecs'
echo '1' > '/sys/module/snd_hda_intel/parameters/power_save'
echo 'min_power' > '/sys/class/scsi_host/host0/link_power_management_policy'
echo 'auto' > '/sys/bus/usb/devices/5-1/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:05:00.2/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1b.0/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1c.0/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1c.1/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1c.2/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1c.3/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1d.1/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1d.2/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1d.3/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1f.1/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1f.2/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:02.0/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:00.0/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1d.0/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:01:00.0/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:02:00.0/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:05:00.0/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:05:00.1/power/control'
echo 'auto' > '/sys/bus/pci/devices/0000:00:1d.7/power/control'
> Factory BIOS and coreboot have different noise.
>
All I'm left is with a very small crackling noise, seemingly coming from
the right handside (where the audio jacks are). A new noise, because I
can't remember ever hearing it :-)
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