How to debug xrandr not setting up the desired resolution?

Question

I need some help in figuring out why does xrandr failes to set the desired resolution.

I have a dual monitor setup:

• 13" laptop preferring 2560x1440 resolution
• 24" monitor preferring 1920x1200 resolution

Because of the high-dpi stuff, I want to push the laptop resolution to 1920x1080 which does not get recognized by the display manager.

I get only this:

2560x1440     59.95*+
1920x1440     60.00  
1856x1392     60.01  
1792x1344     60.01  
1600x1200     60.00  
1400x1050     59.98  
1280x1024     60.02  
1280x960      60.00  
1024x768      60.00  
800x600       60.32    56.25  
640x480       59.94 

To get the modeline, I use:

cvt 1920 1080 

Then to make changes persistent across sessions, I add the following lines into a script in following folder which gets executed during x11 init:

/etc/X11/xinit/xinitrc.d

Contents (add-fullhd-to-edp1.sh):

xrandr --newmode "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync
xrandr --addmode eDP1 1920x1080_60.00

After which I get that the resolution is now supported in xrandr

2560x1440     59.95*+
1920x1440     60.00  
1856x1392     60.01  
1792x1344     60.01  
1600x1200     60.00  
1400x1050     59.98  
1280x1024     60.02  
1280x960      60.00  
1024x768      60.00  
800x600       60.32    56.25  
640x480       59.94  
1920x1080_60.00  59.96

So after I choose the resolution either with xrandr or the GUI I get the screen flashing once while it tries to set the resolution, and then second time for the revert. Entries in Xorg.log while that happens are only framebuffer resizes:

(II) intel(0): resizing framebuffer to 1920x2280
(II) intel(0): switch to mode [email protected] on HDMI1 using pipe 0, position (0, 0), rotation normal, reflection none
(II) intel(0): switch to mode [email protected] on eDP1 using pipe 1, position (0, 1200), rotation normal, reflection none
(II) intel(0): resizing framebuffer to 2560x2640
(II) intel(0): switch to mode [email protected] on HDMI1 using pipe 1, position (0, 0), rotation normal, reflection none
(II) intel(0): switch to mode [email protected] on eDP1 using pipe 0, position (0, 1200), rotation normal, reflection none
(II) intel(0): switch to mode [email protected] on HDMI1 using pipe 0, position (0, 0), rotation normal, reflection none
(II) intel(0): switch to mode [email protected] on eDP1 using pipe 1, position (0, 1200), rotation normal, reflection none

As you can see, I'm have an intel driver, Iris graphics.

00:02.0 VGA compatible controller: Intel Corporation Device 0a2e (rev 09)

Funny thing that this was working fine until some update rolled, I didn't figure out which one broke it.

Any clues? Help is greatly appreciated.

Solution

I posted the bug to gdm developers and got the tip to use static conf.

/etc/X11/xorg.conf.d/21-intel.conf

Contents:

Section "Device"
    Identifier  "Intel Graphics"
        Driver      "intel"
        Option      "monitor-eDP1" "eDP1"
EndSection

Section "Monitor"
    Identifier      "eDP1"
    Modeline "1920x1080"  172.80  1920 2040 2248 2576  1080 1081 1084 1118  -HSync +Vsync
EndSection

And it worked. Funny, I think this really is a bug for the xrandr developers.

Comments

[Panther]

X developers, file against xrandr

[user.dz]

Could you tell me how did you get Modeline "1920x1080" 172.80 1920 2040 2248 2576 1080 1081 1084 1118 -HSync +Vsync and why it is different from xrandr --newmode "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync?

[bassman]

@user.dz I've used different command instead of cvt to generate those. Yeah, I tried everything. :) Those numbers are output of the gtf 1920 1080 60 # 1920x1080 @ 60.00 Hz (GTF) hsync: 67.08 kHz; pclk: 172.80 MHz Modeline "1920x1080_60.00" 172.80 1920 2040 2248 2576 1080 1081 1084 1118 -HSync +Vsync

[user.dz]

Thank you bassman, this is interesting while I'm trying to make my way on graphics debugging. I'll look later for this: why some modes are accepted while others no.