Mailing List Archive

Strange DPMS behaviour
I've been having this strange problem with my dual monitor setup.
While I've figured out the nightmare of auto-detect not working at all
with dual monitors and the inability to use nvidia's configure tool
combined with Plasma's monitor option to fix the problem I've switched
to nouveau and at least it is consistent now and not messing up my
windows and randomly disconnecting.

However, I still have one problem which is getting annoying. DPMS does
not work automatically like it should. It says for the monitors the
capabilities are off. But then it enables it (but it doesn't - xset
shows everything disabled - first two lines are monitors and the last
one is a general message saying it's enabled.)

$ grep -i dpms /var/log/Xorg.0.log
[ 6.087] (II) modeset(0): DPMS capabilities: Off
[ 6.156] (II) modeset(0): DPMS capabilities: Off
[ 6.174] (==) modeset(0): DPMS enabled
[ 6.174] (II) Initializing extension DPMS

Now I can run xset dpms 300 450 600 and only then xset shows it as set:

$ xset q
Keyboard Control:
auto repeat: on key click percent: 0 LED mask: 00000002
XKB indicators:
00: Caps Lock: off 01: Num Lock: on 02: Scroll Lock: off
03: Compose: off 04: Kana: off 05: Sleep: off
06: Suspend: off 07: Mute: off 08: Misc: off
09: Mail: off 10: Charging: off 11: Shift Lock: off
12: Group 2: off 13: Mouse Keys: off
auto repeat delay: 600 repeat rate: 25
auto repeating keys: 00ffffffdffffbbf
fadfffefffedffff
9fffffffffffffff
fff7ffffffffffff
bell percent: 50 bell pitch: 400 bell duration: 100
Pointer Control:
acceleration: 2/1 threshold: 4
Screen Saver:
prefer blanking: yes allow exposures: yes
timeout: 0 cycle: 600
Colors:
default colormap: 0x20 BlackPixel: 0x0 WhitePixel: 0xffffff
Font Path:
/usr/share/fonts/misc,/usr/share/fonts/75dpi,built-ins
DPMS (Display Power Management Signaling):
Standby: 300 Suspend: 450 Off: 600
DPMS is Enabled
Monitor is On

However, while it does blank and turn off the screens it doesn't last.
Maybe 10 seconds later the screens turn back on.

I can force it with xset to turn the monitors off immediately but same
results - after a short time the monitors turn back on. In the X logs
there is this:

[ 449.529] (WW) EDID timing clock 408.29 exceeds claimed max 75MHz, fixing

which makes me wonder if the EDID data is bad on the one monitor (a
Samsung monitor.)

Does anyone know of a way to test this DPMS? I suppose I could try
unplugging the Samsung monitor to see if the problem goes away? One
thing that may make a difference is that the Samsung is HDMI and the
other monitor (MSI) is DP.

However, both of these monitors worked find on my old computer (it was
really old, no UEFI support.

Can anyone think of next steps? I'm running out of things to try...

Dan
Re: Strange DPMS behaviour [ In reply to ]
If you find that the EDID is really bad for one of the monitors, you
should be able to find a correct copy and make that one available to X,
although I don't remember how since I haven't needed to do so in years. 
I believe it is a setting within/under Xorg.conf.

Jack

On 2/6/23 00:36, Daniel Frey wrote:
> I've been having this strange problem with my dual monitor setup.
> While I've figured out the nightmare of auto-detect not working at all
> with dual monitors and the inability to use nvidia's configure tool
> combined with Plasma's monitor option to fix the problem I've switched
> to nouveau and at least it is consistent now and not messing up my
> windows and randomly disconnecting.
>
> However, I still have one problem which is getting annoying. DPMS does
> not work automatically like it should. It says for the monitors the
> capabilities are off. But then it enables it (but it doesn't - xset
> shows everything disabled - first two lines are monitors and the last
> one is a general message saying it's enabled.)
>
> $ grep -i dpms /var/log/Xorg.0.log
> [ 6.087] (II) modeset(0): DPMS capabilities: Off
> [ 6.156] (II) modeset(0): DPMS capabilities: Off
> [ 6.174] (==) modeset(0): DPMS enabled
> [ 6.174] (II) Initializing extension DPMS
>
> Now I can run xset dpms 300 450 600 and only then xset shows it as set:
>
> $ xset q
> Keyboard Control:
> auto repeat: on key click percent: 0 LED mask: 00000002
> XKB indicators:
> 00: Caps Lock: off 01: Num Lock: on 02: Scroll Lock: off
> 03: Compose: off 04: Kana: off 05: Sleep: off
> 06: Suspend: off 07: Mute: off 08: Misc: off
> 09: Mail: off 10: Charging: off 11: Shift Lock: off
> 12: Group 2: off 13: Mouse Keys: off
> auto repeat delay: 600 repeat rate: 25
> auto repeating keys: 00ffffffdffffbbf
> fadfffefffedffff
> 9fffffffffffffff
> fff7ffffffffffff
> bell percent: 50 bell pitch: 400 bell duration: 100
> Pointer Control:
> acceleration: 2/1 threshold: 4
> Screen Saver:
> prefer blanking: yes allow exposures: yes
> timeout: 0 cycle: 600
> Colors:
> default colormap: 0x20 BlackPixel: 0x0 WhitePixel: 0xffffff
> Font Path:
> /usr/share/fonts/misc,/usr/share/fonts/75dpi,built-ins
> DPMS (Display Power Management Signaling):
> Standby: 300 Suspend: 450 Off: 600
> DPMS is Enabled
> Monitor is On
>
> However, while it does blank and turn off the screens it doesn't last.
> Maybe 10 seconds later the screens turn back on.
>
> I can force it with xset to turn the monitors off immediately but same
> results - after a short time the monitors turn back on. In the X logs
> there is this:
>
> [ 449.529] (WW) EDID timing clock 408.29 exceeds claimed max 75MHz, fixing
>
> which makes me wonder if the EDID data is bad on the one monitor (a
> Samsung monitor.)
>
> Does anyone know of a way to test this DPMS? I suppose I could try
> unplugging the Samsung monitor to see if the problem goes away? One
> thing that may make a difference is that the Samsung is HDMI and the
> other monitor (MSI) is DP.
>
> However, both of these monitors worked find on my old computer (it was
> really old, no UEFI support.
>
> Can anyone think of next steps? I'm running out of things to try...
>
> Dan
>
Re: Strange DPMS behaviour [ In reply to ]
On 2/6/23 08:00, Jack wrote:
> If you find that the EDID is really bad for one of the monitors, you
> should be able to find a correct copy and make that one available to X,
> although I don't remember how since I haven't needed to do so in years.
> I believe it is a setting within/under Xorg.conf.
>
> Jack

Strangely enough, I had time to do more testing today. I tried
unplugging each monitor and trying it out forcing DPMS on.

I have two monitors: MSI on DP, and a Samsung on HDMI.

The Samsung is the one with EDID errors but it works fine with DPMS with
the other monitor (MSI) unplugged.

The MSI monitor (with the Samsung monitor unplugged) still has the
problem with random wakes.

Thinking it might be a displayport issue, I hooked my laptop to the hdmi
port on the MSI - same problem... couldn't use the main PC as there's
only one hdmi port on the video card.

So the MSI monitor is at fault here, both hdmi and displayport fail to
use DPMS correctly.

Oddly enough, it's the Samsung with the EDID errors but it is working
fine despite those errors. Go figure...

Alas, now at least I can move on with configuring the rest of the
system. Looks like the only way to fix this problem is to get another
monitor.

Dan