Mailinglist Archive: radeonhd (529 mails)

[Hubert Kario <kario@xxxxxxxxxx>]

On 18 12 2007 18:21:22 Jerome Quelin wrote:
> On 07/12/17 23:12 +0100, Luc Verhaegen wrote:
> > > > You should try using a mode with reduced blanking. I have no idea how
> > > > that can be achieved easily with RandR. With NoRandR, it is trivial
> > > > because you would just state
> > > > Modes "1600x1200R"
> > >
> > > xrandr --output DVI-I_1/digital --mode 1280x1024
> > > works ok to change my resolution...
> > >
> > > but once again, i'd prefer having a non-flickering 1600x1200... do you
> > > know why it happens? if you need some more information from me, don't
> > > hesitate...
> >
> > This is not what reduced blanking means.
>
> oh, sorry. i don't know that much of x stuff.
>
> > 1600x1200 with normal cvt:
> >
> > # 1600x1200 59.87 Hz (CVT 1.92M3) hsync: 74.54 kHz; pclk: 161.00 MHz
> > Modeline "1600x1200_60.00"  161.00  1600 1712 1880 2160  1200 1203 1207
> > 1245 -hsync +vsync
> >
> > 1600x1200 with cvt -r:
> >
> > # 1600x1200 59.92 Hz (CVT 1.92M3-R) hsync: 74.01 kHz; pclk: 130.25 MHz
> > Modeline "1600x1200R"  130.25  1600 1648 1680 1760  1200 1203 1207 1235
> > +hsync -vsync
> >
> > Notice how the bandwidth/dotclock went down from 161MHz to a much more
> > acceptable 130.25 MHz.
> >
> > When you choose this reduced blanking mode, your monitor will be a lot
> > happier, this while displaying the same image at roughly the same
> > timing.
>
> ok. i tried cvt -r 1600 1200 which indeeds reduces to 130MHz:
> $ cvt -r 1600 1200
> # 1600x1200 59.92 Hz (CVT 1.92M3-R) hsync: 74.01 kHz; pclk: 130.25 MHz
> Modeline "1600x1200R"  130.25  1600 1648 1680 1760  1200 1203 1207 1235
> +hsync -vsync
>
> however, the flickering still happens... maybe less intensly, but still
> very incomfortable to use. :-(
>
> any other idea?
> (going back to 1280x1024)

Not sure what your problem really is, but reduced blanking can be used (and 
should be used) only with LCDs not CRTs. As you say that you see flickering I 
deduce you have a CRT so you should use higher refresh rate, I'd recommend 
70Hz for a smaller screens (<19") and 75 for bigger ones.

$ cvt 1600 1200 70
# 1600x1200 69.92 Hz (CVT) hsync: 87.55 kHz; pclk: 190.50 MHz
Modeline "1600x1200_70.00"  190.50  1600 1720 1888 2176  1200 1203 1207 
1252 -hsync +vsync
$ cvt 1600 1200 75
# 1600x1200 74.98 Hz (CVT 1.92M3) hsync: 94.09 kHz; pclk: 204.75 MHz
Modeline "1600x1200_75.00"  204.75  1600 1720 1888 2176  1200 1203 1207 
1255 -hsync +vsync

> thanks,
> jérôme
> --
> jquelin@xxxxxxxxx

hope it helps
hubert

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