Re: PROBLEM: MacBook makes whining noise when usb-uhci active

[Richard Mittendorfer <delist@gmx.net>]

Also sprach "Tim Hull" <thully@umich.edu> (Sat, 7 Jul 2007 19:45:48 -0400):
> [1.] One line summary of the problem: MacBook makes whining noise when
> usb-uhci loaded.
> [2.] Full description of the problem/report: On my MacBook (first
> generation Core Duo 1.83GHz), I can hear a faint whining noise that
> becomes audible when usb-uhci is loaded and remains audible except
> when the USB ports are in use ( i.e. the noise temporarily stops when
> I'm copying music to my iPod).  This problem occurs on both 2.6.21
> and 2.6.22-rc7, but does not occur on 2.6.18.  Unloading usb-uhci when
> booted in 2.6.22-rc7 makes the whining noise stop, but the system is
> useless in this state for obvious reasons.
> [...]
> [4.2.] Kernel .config file:
> [...]
> CONFIG_NO_HZ=y
> [...]
> # CONFIG_HZ_100 is not set
> # CONFIG_HZ_250 is not set
> # CONFIG_HZ_300 is not set
> CONFIG_HZ_1000=y
> CONFIG_HZ=1000
> [...]
> CONFIG_X86_ACPI_CPUFREQ=y
> [...]

This sounds like a known problem w/ some laptops. Maybe powersupply,
noisy onboard conductors at 1000Hz, entering processor P-states and
I've heard about it in context with USB too, IIRC....

As you have tickless timer enabled, CONFIG_HZ shouldn't trigger it, but
you can check this with '$ vmstat 1' and watch the in(terrupts) field.
They should be quite low.

To disable P-states follow the instructions on the link below.

As you have set CONFIG_USB_SUSPEND and it's noisy only when nothing
is connected, unsetting it might be worth a try. But, AFAIK, 2.6.18
already had this feature?

Here's a link to a thinkpad related site talking about it:
http://www.thinkwiki.org/wiki/Problem_with_high_pitch_noises

Looks like there are quite some different reasons causing it.

HTH & good luck,
ritch
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