HPET drift question
From: Alex Williamson
Date: Thu Aug 25 2005 - 10:17:21 EST
Hi Venki,
I'm confused by the calculation of the drift value in the hpet
driver. The specs defines the recommended minimum hardware
implementation is a frequency drift of 0.05% or 500ppm. However, the
drift passed in when registering with the time interpolator is:
ti->drift = ti->frequency * HPET_DRIFT / 1000000;
Isn't that absolute number of ticks per second drift? The time
interpolator defines the drift in parts per million. Shouldn't this
simply be:
ti->drift = HPET_DRIFT;
The current code seems to greatly penalize any hpet timer with greater
than a 1MHz frequency. Thanks,
Alex
--
Alex Williamson HP Linux & Open Source Lab
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