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Old 01-11-10, 12:19 PM   #4
hasfill
Registered User
 
Join Date: Apr 2009
Posts: 5
Default Re: 195.30: same EDID interpreted differently on VGA and DVI connectors! Must be a bu

Thanks for the replies. I should have included more info in my original post,
but was trying to be brief.
I have read http://en.wikipedia.org/wiki/Extende...ification_data, so I expected
byte 20 to differ. That said, that specification did not seem to match the results of a ddcprobe
(via the VGA interface):

vbe: VESA 3.0 detected.
oem: NVIDIA
vendor: NVIDIA Corporation
product: nv40 Board - p212-1 Chip Rev
memory: 131072kb
mode: 640x400x256
mode: 640x480x256
mode: 800x600x16
mode: 800x600x256
mode: 1024x768x16
mode: 1024x768x256
mode: 1280x1024x16
mode: 1280x1024x256
mode: 320x200x64k
mode: 320x200x16m
mode: 640x480x64k
mode: 640x480x16m
mode: 800x600x64k
mode: 800x600x16m
mode: 1024x768x64k
mode: 1024x768x16m
mode: 1280x1024x64k
mode: 1280x1024x16m
edid:
edid: 1 3
id: d01b
eisa: DELd01b
serial: 30445253
manufacture: 44 2009
input: separate sync, composite sync, sync on green, analog signal.
screensize: 51 29
gamma: 2.200000
dpms: RGB, active off, suspend, standby
timing: 720x400@70 Hz (VGA 640x400, IBM)
timing: 640x480@60 Hz (VGA)
timing: 640x480@75 Hz (VESA)
timing: 800x600@60 Hz (VESA)
timing: 800x600@72 Hz (VESA)
timing: 800x600@75 Hz (VESA)
timing: 1024x768@87 Hz Interlaced (8514A)
timing: 1024x768@75 Hz (VESA)
ctiming: 1152x864@75
ctiming: 1280x1024@60
ctiming: 1680x1680@60
dtiming: 2048x1152@59
monitorserial: T940F9AT0DRS
monitorrange: 30-92, 56-85
monitorname: DELL SP2309W

----------------------------------------------------------------------------------------
The same ddcprobe via the DVI-D interface fails:-

vbe: VESA 3.0 detected.
oem: NVIDIA
vendor: NVIDIA Corporation
product: nv40 Board - p212-1 Chip Rev
memory: 131072kb
mode: 640x400x256
mode: 640x480x256
mode: 800x600x16
mode: 800x600x256
mode: 1024x768x16
mode: 1024x768x256
mode: 1280x1024x16
mode: 1280x1024x256
mode: 320x200x64k
mode: 320x200x16m
mode: 640x480x64k
mode: 640x480x16m
mode: 800x600x64k
mode: 800x600x16m
mode: 1024x768x64k
mode: 1024x768x16m
mode: 1280x1024x64k
mode: 1280x1024x16m
edid:
edidfail

---------------------------------------------------

Ok, but I didn't properly explain the problem. It is simple. When the SP2309W monitor is connected
on the VGA interface, all is well. The correct 2048x1152 native resolution is selected.

However, when connected on the DVI-D it cannot be selected unless I use
Option "ModeValidation" "noMaxPClkCheck"
to force the pixel clock check off.

As for the maximum pixel clock on the DVI-D,
http://en.wikipedia.org/wiki/DVI-D says

"The DVI specification mandates a fixed single link maximum pixel clock frequency of 165 MHz, where all display modes that require less than this must use single link mode, and all those that require more must switch to dual link mode."

But Xorg.0.log from the nvidia driver on the DVI-D interface (noMaxPClkCheck on) says:-

(--) Jan 09 20:40:08 NVIDIA(0): Connected display device(s) on GeForce 6800 at PCI:1:0:0:
(--) Jan 09 20:40:08 NVIDIA(0): DELL SP2309W (DFP-0)
(--) Jan 09 20:40:08 NVIDIA(0): DELL SP2309W (DFP-0): 155.0 MHz maximum pixel clock
(--) Jan 09 20:40:08 NVIDIA(0): DELL SP2309W (DFP-0): Internal Single Link TMDS
(II) Jan 09 20:40:08 NVIDIA(0): Assigned Display Device: DFP-0

The DVI cable supplied with the monitor is single link. I suppose I could buy a dual link cable and try that. Could there be a typo somewhere in the driver where "155MHZ" is used instead of
"165MHz"?

However I see

5471: DESCRIPTOR BLOCK 1
5455: Pixel Clock (in 10 kHz) or 0 (55 MSB 54 LSB)

which is 3d3b! This is exactly 156.75MHz! Thus the dvi-edid pixel rate given by the monitor
is correct. So this is certainly a bug in the driver?

Summary: the dvi-edid from the monitor is 156.75MHz, but the driver gets 155MHz?
Conclusion: a bug in 195.30? {Or the monitor edid format confuses the driver somehow?}
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