[Nouveau] help with signal from monitor

[Ilia Mirkin]

On Tue, Jan 26, 2016 at 5:19 PM, don fisher <hdf3 at comcast.net> wrote:
> I am running under openSuse, but trying to avoid most of the GUIs. I cannot
> get xset to blank the screen, so I added consoleblank=600 in the grub file
> to be added to the kernel command line. The system blanks after 10 minutes,
> as expected. The monitor then displays "HDMI/MHL-1 NO SIGNAL", the monitor
> blanks, prints another message that says nothing and the monitor is
> unblanked. I believe that the monitor is sending some sort of "NO SIGNAL"
> message back to the system, which interprets it to mean send the video
> signal again. I assumed that there was a message sent by the monitor,
> interpreted by the driver, and some signal was sent to the OS to unblank the
> monitor. I know no more than this, except that another user on the openSuse
> lists posted a similar complaint relating to an ASUS monitor.

OK that's weird. What happens if you do

sleep 1 && xset dpms force off

I assume the same thing. What could be happening is that the monitor
effectively disconnects (and shows the "no signal" message), and then
reconnects. Then the graphics card notices "hey, a new monitor is
connected", which triggers all the usual "I just plugged in a new
monitor" actions. This would imply that the monitor is messing up
since I'm pretty sure it's not supposed to trigger a hotplug when
blanking.

You could boot with drm.debug=0x1e which should print a ton of info
about what all is going on.

  -ilia