extremely low refresh rate

[Sarek]

Hi!

I need to switch the resolution of my card to 2048x1080 and to a refresh rate of 24 or 48 Hz.
I calculated a new modeline using http://gtf.sourceforge.net and tried to use it. The X.Org log says everything is just fine and it successfully switched to 2048x1080@24, but the connected projector says the refresh rate is at 49.75 Hz.
The result is the same if I change the refresh rate to 48 Hz.

Does anybody know whether it is possible, either technically and with the driver, to switch to such a combination of resolution and refresh rate?

Thanks in advance

[pe1chl]

There is often a confusion about refreshrate when using interlacing.
What one calls "48Hz interlaced", someone else may call "24Hz".

In the past I have tried low refreshrates and it worked. However, recent drivers have a lot more checks and may reject or modify things that you have told them. Look closely to the log, and maybe you need to set one of the override flags that tell the driver that it should listen to you.

[Sarek]

I already looked through the log quite closely, but didn't find anything suspicious, except that the log tells something different regarding the mode switch than the hardware really does...

Where can I find some documentation about those override flags you spoke of?

Thank you very much

[pe1chl]

In the /usr/share/doc/NVIDIA_GLX-1.0/README.txt file that comes with the driver.

[Sarek]

I tried the various parameters from the ReadMe file, but I still get the same results.
I had opened a service inquiry with NVIDIA and now finally got an answer. They say NVIDIA cards can run such a resolution, but the framerate will be 60 Hz.
But I think this is not really correct as I keep getting a framerate of 49.75 Hz.

Any help would be greatly appreciated.

[netllama]

Please start X with the following command:
startx -- -logverbose 6

and then generate and post an nvidia-bug-report.log.

Thanks,
Lonni

[Sarek]

Sorry for the long delay, but i can't access that projector at all times.
After I upgraded the drivers to the most recent version (without any difference in the behaviour) I now managed to generate a nvidia-bug-report.log but unfortunately I am not able to upload it, because it's too big.

I instead uploaded them to some webspace I can access:
http://www.uliweb.de/nvidia-bug-report.log
http://www.uliweb.de/Xorg.0.log

[netllama]

According to the EDID in your bug report, there is a 2048x1080@50Hz mode which is valid. I'm not clear where you are seeing that 2048x1080 is valid for any other refresh rate:

(II) NVIDIA(1): Validating Mode "2048x1080":
(II) NVIDIA(1): 2048 x 1080 @ 50 Hz
(II) NVIDIA(1): Mode Source: EDID
(II) NVIDIA(1): Pixel Clock : 122.00 MHz
(II) NVIDIA(1): HRes, HSyncStart : 2048, 2096
(II) NVIDIA(1): HSyncEnd, HTotal : 2128, 2208
(II) NVIDIA(1): VRes, VSyncStart : 1080, 1083
(II) NVIDIA(1): VSyncEnd, VTotal : 1093, 1106
(II) NVIDIA(1): H/V Polarity : +/+
(II) NVIDIA(1): Mode is valid.

Does requesting a 2048x1080 mode (without a modeline) work?

[Sarek]

Well, firstly the projector's specs say so.
2048x1080 is supported twice:
2048x1080 at 23-48 Hz is supported including cinema processing (which is what I want) and
2048x1080 at 23-72 Hz is supported without cinema processing (which is what I do not want)

Secondly, the projector's EDID response tells me so:
(--) NVIDIA(1): Valid HSync Range : 11 kHz - 197 kHz
(--) NVIDIA(1): Valid VRefresh Range : 23 Hz - 96 Hz
(--) NVIDIA(1): EDID maximum pixel clock : 170.0 MHz

Neither HSync, VRefresh nor the maximum pixel clock are exceeded by my modeline.

Just requesting "2048x1080" does work, the display is set to 49.75 Hz, so I assume the 2048x1080@50 mode supplied by the EDID is used.

[netllama]

Does the projector manufacturer (TEX?) provide mode timings? Without them, there's no obvious way of getting anything outside of the EDID defined modes to work.

Thanks,
Lonni