Bug#424868: Noise from backlight electronics with new kernel 2.6.18 for PowerPC
Source: linux
Version: 2.6
After Updating to etch and kernel 2.6.18 a whining very high frequency
noise is hearable. The same noise was also hearable with kernel-2.6.8
but only if backlight intensity was not at maximum level
As with the old kernel the noise frequency changes with backlight
intensity change, but is not disapearing with maximum intensity with
the new kernel. Upon boot the noise is not present until the line:
pmubl: Backlight initialized (pmubl)
appears. Therefore I think that the new kernel has limited the
backlight level to value slighly bellow the hardware limit.
The above stated console log line is issued by code in
drivers/macintosh/via-pmu-backlight.c
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