lkml.org 
[lkml]   [2001]   [Sep]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: CPU frequency shifting "problems"
Eric W. Biederman wrote:
> > What does exist is the bus clock (well, a multiple of it, but you get the
> > idea), and that one is stable. I bet PCI devices don't like to be randomly
> > driven at frequencies "somewhere between 12 and 33MHz" depending on load ;)
>
> I doubt they would like it but it is perfectly legal (PCI spec..) to
> vary the pci clock, depending upon load.

Yes it is. Also, the PCI clock is frequency modulated to reduce
electrical interference. (Or on a more cynical note, to pass the
official emissions tests ;-)

However it's common practice to PLL to the PCI clock, for clock
distribution on a board, so varying the frequency must be done in a
strictly constrained fashion.

-- Jamie
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:03    [W:0.116 / U:1.564 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site