From: Alex Williamson <alex.williamson@hp.com>
To: venkatesh.pallipadi@intel.com
Cc: robert.picco@hp.com, linux-kernel@vger.kernel.org
Subject: HPET drift question
Date: Thu, 25 Aug 2005 09:17:08 -0600 [thread overview]
Message-ID: <1124983028.5331.15.camel@tdi> (raw)
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
next reply other threads:[~2005-08-25 15:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-25 15:17 Alex Williamson [this message]
-- strict thread matches above, loose matches on Subject: below --
2005-08-27 0:53 HPET drift question Pallipadi, Venkatesh
2005-08-28 14:03 ` Bob Picco
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