How to find HorizSync / VertRefresh rates?

[Ted Mittelstaedt]

> -----Original Message-----
> From: owner-freebsd-questions at freebsd.org
> [mailto:owner-freebsd-questions at freebsd.org]On Behalf Of Victor Engmark
> Sent: Tuesday, May 01, 2007 12:28 AM
> To: Greg 'groggy' Lehey
> Cc: FreeBSD Questions
> Subject: Re: How to find HorizSync / VertRefresh rates?
>
>
> On 5/1/07, Greg 'groggy' Lehey <grog at freebsd.org> wrote:
> >
> > On Monday, 30 April 2007 at 11:02:54 +0200, Victor Engmark wrote:
> > > I'm trying to create a pristine xorg.conf, but I've been unable to
> > > find proper values for HorizSync and VertRefresh for my Dell Latitude
> > > D610.
> > >
> > > I've tried the values presented in MonitorsDB
> > >
> <http://sources.gentoo.org/viewcvs.py/gentoo/src/hwdata/MonitorsDB
> ?view=markup
> > >
> > > for "Dell 1400x1050 Laptop Display Panel", which are HorizSync
> > > 31.5-90.0 and VertRefresh 59.0-75.0, but I get a warning in
> > > /var/log/Xorg.0.log for both of them saying they are "not within DDC
> > > ranges."
> > >
> > > I've tried looking around the Dell web pages, but I haven't found any
> > > pages mentioning these parameters (not too surprising, really).
> > >
> > > I've tried to leave these settings out, but even then I get a warning:
> > > (WW) I810(0): config file hsync range 60-66.3158kHz not
> within DDC hsync
> > > ranges.
> > >
> > > I'm wondering if this has anything to do with the other warnings I get
> > > during startup:
> > > (WW) I810(0): Bad V_BIOS checksum
> > > and
> > > (WW) I810(0): Extended BIOS function 0x5f05 failed.
> >
> > This, along with the follow-ups, reminds me of a problem I had with a
> > Dell Inspiron 5100 some years ago.  In that case, X didn't map the
> > video BIOS correctly, and so it wasn't able to read the information
> > from the BIOS.  The information includes things like the panel
> > geometry, which in my case was being reported as 65535x65535 pixels.
> > In your case we have:
> >
> > >  # From Xorg.0.log
> > >  DisplaySize  286 214
> >
> > That's clearly wrong too.
>
>
> It's equal to the values in the
> documentation<http://support.euro.dell.com/support/edocs/systems/l
> atd610/en/ug_en/specs.htm>,
> rounded off to integers.
>

I feel the need to remind folks that the concept of refresh rates is
completely meaningless with LCD panels.  Flatpanels do not have a single
scan gun that draws lines at a specific time and rate of speed across a
phosphor.

The computer in the LCD panel takes the video input at a range of refresh
rates, and converts it to a bitmapped image that is fed to the display
crystals.  You can use whatever horizontal and vertical refresh rates
you want, as long as they are in the table that the LCD panel's computer
can decode, the resulting output is the same.

I also will remind people that the pixel counts as resolution on flatpanels
also have no meaning.  A flat panel has a fixed natural resolution.  Any
other resolution that you feed to it is either dithered up or dithered
down to match the actual resolution by the display computer in the flat
panel.

Ted