Resolutions beneath 1024x768 cut the bottom of the screen (linux ubuntu)

[vervelover]

Hi, I'm experiencing a problem under linux Ubuntu Gutsy Gibbon with all nvidia drivers I tryed (also with the latest 169.09). If I set a screen resolution beyond 1024x768, like 800x600, the bottom part of the screen is cut (for example, I can't see the penguins in Frozen Bubble, only the arrow). My card is a Nvidia geforce go 7400 turbocash 256mb, my laptop is a Medion RIM2510. Anyone can help?
Thanks in advance
vervelover

[vixt]

I encountered something similar with my 6600GT (AGP-slot), but only with 800x600 resolution.
I solved it by installing the old 100.14.19 driver.

[lloeki]

I encountered the same problem but traced the source of the problem. read on for details.

with DynamicTwinView the xrandr command outputs a list of available resolutions to choose from. bote that refresh rates are wrong and abused as a workaround until xrandr 1.2 support. see the readme for that.
so I tested each resolution by hand.

$ xrandr -s FOOxBAR

to revert to the default one in case of unreadable screen I just blindly typed:

xrandr -s 0

which switches to the first one in the list (you can do 1 2 3 4 etc as shorthands for the others). this resulted in very wrong display, either cut of as you described when it overflowed down, or wrapped around if it was overflowing on the right, or both.

but now, with DynamicTwinView disabled, we can see what the REAL refresh rates are. now xrandr outputs:

$ xrandr 
Screen 0: minimum 320 x 240, current 1280 x 800, maximum 1280 x 800
default connected 1280x800+0+0 0mm x 0mm
   1280x800       60.0* 
   1280x768       60.0  
   1280x720       60.0  
   1024x768       60.0  
   640x400       120.0  
   512x384       120.0  
   400x300       121.0  
   320x240       120.0  
   960x600       120.0  
   960x540       120.0  
   840x525       120.0  
   800x600       120.0     60.0  
   800x512       121.0  
   720x450       120.0  
   680x384       120.0  
   640x512       120.0  
   640x480       120.0     60.0  
   640x384       120.0  
   640x360       120.0  
   576x432       120.0

xrandr will choose 120Hz over the 60Hz variant, since it's in its view (and he obviously should be right according to the info he has) this is the best choice.

but as I use a laptop DFP, 120Hz is out of question... and results in wrong timings, thus the visual issues above.

now try

xrandr --rate 60 -s 800x600

and behold, all is fine.

so the right thing to do now is to enable X or the nvidia driver to drop out modes with refresh rates about 60Hz. then xrandr will only show the good 60Hz variants and all will be fine.

[lloeki]

unfortunately I tried

Option "ModeValidation" "DFP-0: ObeyEdidContradictions"

which didn't exclude modes

also interesting modevalidation options are:
- AllowNon60HzDFPModes
- AllowInterlacedModes
- NoVertRefreshCheck
but we wan tthe OPPOSITE of them! that is manually set a cap

there's also normal options:
- UseEdidFreqs
- ExactModeTimingsDVI
but these fail to help, even resulting in a black screen since I have no modelines.

[lloeki]

I made progress, a la old way.

in xorg.conf, monitor section, I added:

    VertRefresh     55.0 - 65.0

which did not prevent xrandr from listing bad modes

then I switched to each correct (60hz) mode with xrandr, started xvidtune and pressed 'show' button, which displays the modeline on the console.

I then copy-pasted those modelines into the monitor section:

    Modeline "1280x800"     83.50   1280 1352 1480 1680    800  803  809  831 -hsync -vsync
    Modeline "1280x768"     80.14   1280 1344 1480 1680    768  769  772  795 -hsync +vsync
    Modeline "1280x720"     74.48   1280 1336 1472 1664    720  721  724  746 -hsync +vsync
    Modeline "1024x768"     65.00   1024 1048 1184 1344    768  771  777  806 -hsync -vsync
    Modeline "800x600"      40.00    800  840  968 1056    600  601  605  628 +hsync +vsync
    Modeline "640x480"      25.18    640  656  752  800    480  490  492  525 -hsync -vsync
    Modeline "640x400"      41.73    640  672  740  840    400  200  201  207 -hsync +vsync doublescan

    Modeline "512x384"      32.50    512  524  592  672    384  192  194  201 -hsync -vsync doublescan

    Modeline "400x300"      20.00    400  420  484  528    300  150  151  157 +hsync +vsync doublescan

    Modeline "320x240"      12.59    320  328  376  400    240  122  123  131 -hsync -vsync doublescan

note that this is specific to my screen, so don't use this, this might cause problems with your screen.

and here's the xrandr output:

$ xrandr
Screen 0: minimum 576 x 360, current 1280 x 800, maximum 1280 x 800
default connected 1280x800+0+0 0mm x 0mm
   1280x800       60.0* 
   1280x768       60.0  
   1280x720       60.0  
   1024x768       60.0  
   800x600        60.0  
   640x480        60.0  
   960x600       120.0  
   960x540       120.0  
   840x525       120.0  
   800x512       121.0  
   720x450       120.0  
   680x384       120.0  
   640x512       120.0  
   640x384       120.0  
   640x360       120.0  
   576x432       120.0

and now it works like a charm, although those weird 120hz remaining modes are a no-go.
note also that some modes have disappeared (the doublescan ones), although I have them listed in modelines and previously working...

[lloeki]

I commented out every modeline except the ones that have both 120 and 60 rates, i.e 800x600 and 640x480, and I have both those two previously failing res working and the previously working but disappearing ones back again.

now what could I do to either shove off non-working weird modes from the list or make thme work? I don't know.

PS: to have the next and previous xvidtune buttons working you need to add this to your Screen section:

    SubSection     "Display"
        Depth       24
	    Modes      "1280x800" "1280x768" "1280x720" "1024x768" "800x600" "640x480" "640x400" "512x384" "400x300" "320x240"
    EndSubSection

This will have the nice effect to sort xrandr resolutions in the order you want.

[pe1chl]

To get rid of those silly 120 Hz modes and other crap, try:

Option "ModeValidation" "NoVesaModes,NoXServerModes,NoPredefinedModes"

[ctheo]

this is doublescan problem
it only works correctly for 640x400resolution on my 1280x800lcd screen

There is one option that most likely will solve this problem (haven't tried yet myself for some odd reason)

Option "ModeValidation" "string"

"DoubleScanPriority": on GPUs older than G80, doublescan modes are
sorted before non-doublescan modes of the same resolution for
purposes of modepool sorting; but on G80 and later GPUs, doublescan
modes are sorted after non-doublescan modes of the same resolution.
This token inverts that priority (i.e., doublescan modes will be
sorted after on pre-G80 GPUs, and sorted before on G80 and later
GPUs).

[lloeki]

- No*Modes leaves me with only 1280x800, which is the only mode defined by my DFP EDID (checked with 'acquire edid' in nvidia-settings, then "cat edid.bin | parse-edid"). too bad. what's more, some 120Hz modes are perfectly valid. I'll just carefully avoid the bad ones.

- DoubleScanPriority indeed inverts 120 and 60 in xrandr output, putting 60 before. excellent, no more modelines fiddling.

thank you.

[ctheo]

what's the point of double scan on lcd anyway? my eyes can't see the difference (I remember seeing the difference on crt though back in old times)

[pe1chl]

The "NoVesaModes,NoXServerModes,NoPredefinedModes" thing is useful to delete all modes that the server and driver come up with, and only leaves the modes that the display says it supports. This means a display that does not need or want any doublescan modes will not have them in the xrandr list.
When your display only declares one mode, it is not ideal (but that is a problem of the display).
On my display that config command really trims the useless modes and leaves only what I need.