Arch Linux

gonX

Member

From: Denmark

Registered: 2009-08-16

Posts: 112

60Hz LVDS enforced on Lenovo ThinkPad L530, in spite of xrandr output

Hi,

After remembering that my L530 used to run at 50 Hz in Windows on battery, I sought out to replicate the same feature on Linux using some local scripting.
However, my adventures were quickly brought to an end trying to get the 50 Hz mode working in the first place.

Setting the 50 Hz mode - in fact, setting any nonstandard mode - will simply continue having the display set to approx. 60 Hz, despite what xrandr says.

Here's the output I'm getting from xrandr from a fresh reboot:

$ xrandr
Screen 0: minimum 320 x 200, current 1600 x 900, maximum 8192 x 8192
LVDS-1 connected primary 1600x900+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1600x900      60.22*+  59.99    59.94    59.95    50.01    59.82  
   1400x900      59.96    59.88  
   1440x810      60.00    59.97  
   1368x768      59.88    59.85  
   1280x800      59.99    59.97    59.81    59.91  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   684x384       59.88    59.85  
   640x400       59.88    59.98  
   640x360       59.86    59.83    59.84    59.32  
   512x384       60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
VGA-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
HDMI-3 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)

As indicated by the star, the display is set to 60 Hz. I can confirm this by running glxgears for a couple of seconds, which confirms that I have 301 frames over 5.0 seconds (roughly 60 FPS).

Setting the display to the EDID-reported 50 Hz mode seems to work based off what xrandr reports:

$ xrandr --output LVDS-1 --mode 1600x900 --refresh 50
$ xrandr | grep 1600x900 
LVDS-1 connected primary 1600x900+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1600x900      60.22 +  59.99    59.94    59.95    50.01*   59.82  

However, running glxgears, it still reports a 60 FPS rate, and I definitely do not see the resulting image being choppier as expected:

$ glxgears
305 frames in 5.0 seconds = 60.887 FPS
301 frames in 5.0 seconds = 60.121 FPS
301 frames in 5.0 seconds = 60.121 FPS
301 frames in 5.0 seconds = 60.121 FPS
^C

Stuff I've tried:
- Adding and making my own modelines using both cvt and gtf for modeline generation, and xrandr for adding and enabing the modelines. Even as low as 2 Hz and as "high" as 75 Hz seems to work perfectly fine with the display but with no change in neither console nor graphical output from glxgears. (FWIW Retroarch reports 60 FPS on these exotic modes as well)
- Going back to a LTS version of Linux 4.1 with no change in behavior.

I'm on the latest system updates as of this post. I have no idea if this has ever worked on my laptop on Linux given the few use cases of 50Hz.

---

since 2009