i810 vs. intel: frequency differences?

Adam Jackson ajackson at redhat.com
Fri Apr 13 17:47:34 UTC 2007


On Fri, 2007-04-13 at 10:37 -0700, Tom London wrote:
> On 4/13/07, Adam Jackson <ajackson at redhat.com> wrote:
> > On Fri, 2007-04-13 at 09:39 -0700, Tom London wrote:
> > > Running xorg-x11-drv-i810-1.6.5-19.fc7, I've noticed that seem to
> > > drive different monitor frequencies for the same
> > > monitor/settings/xorg.conf.
> > >
> > > Running on two different LCD monitors, if my xorg.conf says 'i810', I
> > > consistently get Horiz rate of 79.8kHz and Vert rate of 74.6Hz.
> > >
> > > If I only change i810->intel and restart X, I consistently get Horiz
> > > rate of 83.0kHz and Vert rate of 77.8Hz (the last is above supported
> > > rate (~75Hz) for both monitors).
> >
> > The X log, at least for the intel run, should show the exact timings
> > being sent to the monitor, as well as what the monitor reports for
> > capabilities.  That said, there could easily be bugs in the intel
> > driver.
> >
> > > I've also noticed inconsistencies between the rates reported by my
> > > monitors and that reported by xrandr when I run with 'intel': xrandr
> > > reports Horiz is 80kHz (vs. monitor reporting 83kHz) and Vert is 75Hz
> > > (vs. monitor reporting 77.8Hz).
> >
> > Rounding error.  Monitors are not particularly smart.
> >
> > - ajax
> >
> Would normally agree about 'rounding error', but setting the driver to
> 'intel' puts 2 monitors 'out of range' for Horiz.  Also, the monitors
> have no problem reporting 74.6 for 'i810' vs. 77.8 for 'intel'.  There
> must be a difference in the actual signal.  No?
> 
> What exactly from Xorg.0.log would be useful for me to provide?

The whole thing, in a bug report, preferably.

- ajax




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