dpms blanking on laptop panel broken between 410 and 418

Dear support,

I am running my laptop with an external screen attached.

On 410 when I run ‘xset dpms force off’ or wait long enough, both internal and external screens enter dpms powersave mode. The external screen turns its backlight off. The internal screen is blanked (as it does not support DPMS power saving very well).

On 418 when I do the same, only the external monitor enters DPMS powersave mode. The internal screen stays lit always.

There do not seem to be any significant differences in Xorg.0.log or dmesg.
nvidia-bug-report.log.gz (1.28 MB)

dmesg k4.19 m418.txt (109 KB)

Xorg.0.log k4.19 m418.txt (668 KB)

Xorg.0.log k4.19 m410.txt (640 KB)

dmesg k4.19 m410.txt (95.3 KB)

Might be related to the new HardDPMS option which is now enabled by default. I suspect you can return to the previous behaviour by adding

Option "HardDPMS" "false"

to the device section of your /usr/share/X11/xorg.conf.d/20-nvidia-modedebug.conf