[coreboot] Investigating the high pitched noise on the x60 tablet
info at gluglug.org.uk
Tue Jun 10 08:25:18 CEST 2014
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Go to tunables.
Turn everything in "tunables" to "Good" and the noise goes away.
Do this without idle=halt or processor.max_cstate=2 options.
This plus backlight support (see
http://libreboot.org/howto.html#x60_native_notes) you can get battery
life as high as on lenovo bios without any of that noise.
On 09/06/14 22:56, Peter Stuge wrote:
> Charles Devereaux wrote:
>> I would like to investigate the whining noise issue.
>> I have a spare motherboard that I'm setting up for studying this
>> noise issue by pinpointing from which component it comes from
>> by default going into a power saving mode that make this noise.
> The noise is not created by a particular state.
> 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.
> idle=halt skips all C-states.
> uhci_hcd requires the CPU to run every ms.
> Factory BIOS and coreboot have different noise.
> Thermal shutdown is fairly easy to induce when running coreboot,
> but not with factory BIOS. X60 has notoriously poor thermal design,
> but still there is no thermal shutdown with factory BIOS. Find
> Understanding the thermal issue might be helpful for the noise
> Learn how the factory BIOS manages the CPU power states.
> You will not be able to find the documentation you may want for
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