Re: writing a cpufreq driver

[Dave Jones <davej@redhat.com>]

On Thu, Sep 21, 2006 at 02:38:22PM -0500, Langsdorf, Mark wrote:
 > >  > 1.  The first time cpufreq changes speed, I get the whole 
 > > "Losing some
 > >  > ticks... checking if CPU frequency changed." then 
 > > eventually "Losing too
 > >  > many ticks!" and timer switches to PIT.  This does not 
 > > happen when I use
 > >  > the /dev/toshiba driver to change speeds from userspace.  
 > > Not sure what
 > >  > is going on here...  SMI handler latency is between 6 and 7 ms.
 > > 
 > > Is loops_per_jiffy being correctly scaled on a speed transition?
 > > Hmm, powernow-k7.c seems to be the only driver that's calling 
 > > recalibrate_cpu_khz()
 > 
 > Do drivers need to be doing that?  I would have thought the
 > time could would do it after receiving the notification.

Looking at it again..
cpufreq_notify_transition() is calling adjust_jiffies()
which should be doing the same thing, so we should be good to go.

It looks like feasible that recalibrate_cpu_khz() could actually
be killed off.

	Dave