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Siduction Forum => Hardware - Support => Topic started by: oneself on 2014/11/19, 05:35:21

Title: Force Monitor Refresh Rate
Post by: oneself on 2014/11/19, 05:35:21

Hi,

I'm using a Lenovo X230 (http://shop.lenovo.com/us/en/laptops/thinkpad/x-series/x230/) laptop with an external LG-34UC97-S (http://www.lg.com/us/monitors/lg-34UC97-S-ultrawide-monitor) monitor. I've turn off the internal monitor and hooked up the external via HDMI. Looking at the user manual (http://www.lg.com/us/support-product/lg-34UC97-S#), native resolution and refresh rate which should be 3440x1440 50Hz (page 29). However, the monitor is currently running at 3440x1440 29.99Hz, for some reason. I've tried adding 50Hz as follows:

Code: [Select]

$ cvt 3440 1440 50
# 3440x1440 49.96 Hz (CVT) hsync: 74.14 kHz; pclk: 344.00 MHz
Modeline "3440x1440_50.00"  344.00  3440 3672 4040 4640  1440 1443 1453 1484 -hsync +vsync
$ xrandr --newmode "3440x1440_50.00"  344.00  3440 3672 4040 4640  1440 1443 1453 1484 -hsync +vsync
$ xrandr --verbose --addmode HDMI2 "3440x1440_50.00"
$ xrandr --output HDMI2 --mode "3440x1440_50.00"
xrandr: Configure crtc 1 failed

I'm guessing that the modeline returned by cvt is wrong, but I'm not sure how to get the right one. Any help would be appreciated.

Title: Re: Force Monitor Refresh Rate
Post by: dibl on 2014/11/19, 17:27:38

What outputs does

Code: [Select]

$ xrandr
Give you?

Title: Re: Force Monitor Refresh Rate
Post by: oneself on 2014/11/20, 01:02:16

Before running the lines mentioned above it looks like this:

Code: [Select]


Screen 0: minimum 320 x 200, current 3440 x 1440, maximum 8192 x 8192
LVDS1 connected (normal left inverted right x axis y axis)
   1366x768      60.02 +
   1360x768      59.80    59.96 
   1024x768      60.00 
   800x600       60.32    56.25 
   640x480       59.94 
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 connected 3440x1440+0+0 (normal left inverted right x axis y axis) 800mm x 335mm
   3440x1440     29.99*
   2560x1080     60.00 
   1920x1080     59.99    60.00    59.94 
   1680x1050     59.88 
   1600x900      59.98 
   1280x1024     60.02 
   1280x800      59.91 
   1152x864      59.97 
   1280x720      60.00    59.94 
   1024x768      60.00 
   800x600       60.32 
   720x480       60.00    59.94 
   640x480       60.00    59.94 
HDMI3 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)


Title: Re: Force Monitor Refresh Rate
Post by: dibl on 2014/11/20, 01:20:40

I think you must respect the xrandr output, over the user manual. 

Title: Re: Force Monitor Refresh Rate
Post by: oneself on 2014/11/20, 02:46:18

I think the manufacturer knows what their screen is capable of.  I don't think xrandr is reading this monitor's configuration correctly.

Title: Re: Force Monitor Refresh Rate
Post by: dibl on 2014/11/20, 14:35:30

Quote from: oneself on 2014/11/20, 02:46:18

I think the manufacturer knows what their screen is capable of.

Yes, of course they do, but they don't know what OS and driver you are using.

Quote

I don't think xrandr is reading this monitor's configuration correctly.

If the GPU driver doesn't support 50Hz at the high resolution, then xrandr might be reading it correctly.  I am only speculating, but I would investigate the capabilities of your installed driver/kernel module, on the specific GPU in your hardware.