# Re: ghosting with nvidia framebuffer (pci-e 6600), 1600x1200 and 12x22 font

- From: Jurriaan Kalkman \<hidden\>
- Date: 2005-07-22 06:35:53 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2005/07/13455184
- Thread: https://ratatoskr.run/linux-fbdev/2005/07/13455153/t.md

```text
> On Thursday 07 July 2005 03:04, jurriaan wrote:
>> Kernel command line: root=/dev/hda1 video=nvidiafb:1600x1200-32@85
>> atkbd.softrepeat=1
>>
>> nvidiafb: nVidia device/chipset 10DE0141
>> nvidiafb: PCI device 10de:0141 (nVidia Corporation)
>> nvidiafb: CRTC0 found
>> nvidiafb: CRTC1 found
>> nvidiafb: CRTC 0 appears to have a CRT attached
>> nvidiafb: Using CRT on CRTC 0
>> nvidiafb: MTRR set to ON
>> Console: switching to colour frame buffer device 133x54
>> nvidiafb: PCI nVidia NV14 framebuffer (64MB @ 0xC0000000)
>>
>> I'm running at 1600x1200 resolution with the 12x22 font, and a
>> 2.6.13-rc1-mm1 kernel.
>>
>> A strange effect is noticeable: often characters from the left of the
>> screen are ghosted on the right of the screen. Not all of the pixels
>> that form a character, but enough to be visible. To my best knowledge,
>> the ghosting starts at column 85, and 85 * 12 = 1020, which may mean
>> some sort of erroneous wrap-around at pixel 1024 is taking place?
>>
> It looks like a timings problem.  Are the effects still present if you try
> to change modes?

I'll try that later tonight, when I'm home again.
However, whatever corruption is on screen, when I switch virtual consoles
from tty1 to 2 and back (alt-f2 alt-f1), it disappears completely. Until I
force the screen to scroll up by pressing return at the last line, then
they reappear again.

If it was a timings problem, I wouldn't expect switching virtual consoles
to remedy it, nor scrolling the screen up to reproduce it.

>
> Based on the dmesg snippet, I don't think the driver was able to grab the
> edid.  Which means that the mode 1600x1200 was taken from the default
> modedb which may not be correct for your hardware.

It's an Eizo F931 monitor, capable of running 1800x1440@85 without any
trouble in X.org (where no corruption at all is evident, BTW). The monitor
is connected through a Vista Rose KVM switch. IIRC, x.org did manage to
get EDID info, I'll also post that log.

>
> If you can, grab X's modeline using xvidtune, then convert it into a fb
> compatible modeline, enter it in /etc/fb.modes then use fbset to change
> your
> video mode.
>
I'll try that and get back to you, but I'm not convinced it's timing. I
seem to remember disabling all acceleration also fixed the corruption. I
will also test that.

Todo:

1) change modes
2) x.org log wrt. EDID
3) noaccell
4) different fontsize

Thanks,
Jurriaan



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