[PATCH] xfree86: Bump classic driver default to 1024x768

[Adam Jackson]

On Wed, 2010-11-24 at 11:38 -0800, Keith Packard wrote:
> On Mon, 15 Nov 2010 11:25:13 +1000, Peter Hutterer <peter.hutterer at who-t.net> wrote:
> 
> > +	if (!scrp->monitor->maxPixClock && !specified) {
> > +            type = "default ";
> > +            scrp->monitor->maxPixClock = 65000.0;
> > +        }
> 
> Can you explain this part? Seems like this goes beyond changing the
> default mode to 1024x768.

Because sync ranges aren't enough on their own.  They limit how fast the
beam sweeps back and forth, but that's not the same as limiting the
number of pixel samples in the beam output:

% gtf 1280 768 60

  # 1280x768 @ 60.00 Hz (GTF) hsync: 47.70 kHz; pclk: 80.14 MHz
  Modeline "1280x768_60.00"  80.14  1280 1344 1480 1680  768 769 772 795  -HSync +Vsync

% gtf 1024 768 60

  # 1024x768 @ 60.00 Hz (GTF) hsync: 47.70 kHz; pclk: 64.11 MHz
  Modeline "1024x768_60.00"  64.11  1024 1080 1184 1344  768 769 772 795  -HSync +Vsync

Imagine sync ranges as drawing curves on the X-Y graph, making a box
enclosing the possible resolutions.  The upper-right corner of that box
is pretty much unlimited, unless you add the curve for pixel clock which
makes this nice hyperbola to chop that corner off.

Now if it seems to you wrong that we're trying to overlay magic values
on this logic to get the right defaults picked... well, good, that means
you have taste.

- ajax
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