mate-settings-daemon (1.24.1-1) reverts resolution when using custom 23.976Hz modeline

[Drag0nFly]

Expected behaviour

When issuing an xrandr command to switch mode, in my case from 60Hz to a 23.976Hz mode, either from the DE or within a media player application, the mode should be set active unless explicitly switched back by a media player or manually using xrandr --mode in the desktop environment.

Actual behaviour

Immediately after issuing the modeswitch to 23.97610Hz, this is intercepted by mate-settings-daemon and the mode subsequently switched back to a default probed mode (which in this case is a 60Hz mode).

Also, when issuing an xrandr query (“xrandr -q”) when running in this valid, custom modeline recognized by the video driver (in this case, i965), the mate-settings-daemon intercepts this and falls back to the first probed mode (a 1920x1080 60Hz mode.)

Steps to reproduce the behaviour

• Define a custom modeline in xorg.conf or the appropriate xorg.conf.d file, in this example:
  Modeline "1920x1080@23.97610" 74.230 1920 2560 2604 2752 1080 1084 1089 1125 +hsync +vsync

• restart Xorg and verify modeline with “xrandr -q” and manually switching to it using, in this example, “xrandr --output HDMI2 --mode 1920x1080@23.97610 -r 23.98”

• verify the actual custom modeline is being used at the sink (in this case, a projector)

• issue “xrandr -q”

• observe in Xorg.0.log that the mode reverts back to a default, probed mode (in this case, a 60Hz mode).

• when playing video, this occurs instantaneous when mate-settings-daemon is running.

MATE general version

1.24.1-1

Package version

1.24.1-1

Linux Distribution

ArchLinux / Parabola Linux libre

Link to bugreport of your Distribution (requirement)

This is not a distribution-specific issue. The same behaviour occurs with Linux Mint.
Working mate-settings-daemon version is 1.6.0

Comments

To add, the custom modeline above has been used over a number of years on my media server. Somewhere between the 1.6.x version of MATE and associated mate-settings-daemon, the behaviour changed to "disqualify" a custom modeline. (previously verified with Linux Mint 17)

When removing, or killing, mate-settings-daemon, the behaviour works as expected. However, this obviously impedes other configuration management within MATE, and is not a good solution.

I can provide Xorg.0.log files and also verified this using strace on the running mate-settings-daemon.