All of lore.kernel.org
 help / color / mirror / Atom feed
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


             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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1124983028.5331.15.camel@tdi \
    --to=alex.williamson@hp.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=robert.picco@hp.com \
    --cc=venkatesh.pallipadi@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.