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-   -   Screen turn off / on (power management) (https://displaylink.org/forum/showthread.php?t=66243)

schmoo 08-31-2018 08:36 AM

Screen turn off / on (power management)
This is probably a windows insider issue, but given we are close to the final release its probably worth highlighting:

When my monitors go to sleep (but the laptop is still awake) and are "re-awoken" (mouse move etc.). The displaylink monitor will fail to turn back on. It is still registered as a monitor and I can move my mouse + apps to from it, but it is still "off".

Unplug/re-plug will make it work again.

Software Package Version: 8.6.1104.0
Software Package Date: 25th July 2018

DisplayLink Ethernet Driver Version: 8.6.587.0
DisplayLink Audio Driver Version: 8.6.1097.0

Windows 10 Build 17746.rs5_release.180821-1736

Targus USB3.0 DV Dock with Power

AlbanRampon 08-31-2018 01:59 PM

Hello Schmoo,

Thank you for taking the time to report that.
Windows and the dock both seem to believe the screen is up and running as you can move content to it and it's "recognised".

Would you have details about the monitor, please? Model, Revision and how it is connected to the device?
Could you also confirm the dock reference is ACP71?
I'd like us to try and reproduce this issue in-house.

If you could provide the logs gathered with our support tool, that would also be most helpful. If you click gather just after you recover, it will show me what Windows did before: did we get the signal or not. The last link of my forum signature gives the tool. You can upload the zip here as only employees will be able to download it.

Kind regards,

schmoo 09-02-2018 09:24 AM

1 Attachment(s)
ACP71 - Yes
Monitor is a Dell E248WFP connected via DVI

Comes out of sleep ok (power light goes from orange to green), but screen is black (that deep powered off black, no back lights).

I have also applied the regedit night light "hack" (this should be enabled by default IMO).

Issue exists in the beta and gold (displaylink) releases.

Log attached

Everything was working 100% prior to installing the windows insider release.

Going into / coming out off sleep works fine (and is my workaround)

AlbanRampon 09-02-2018 09:51 AM

Thank you for the details,

Can you please try again without the regedit hack?
It would be enabled by default if the feature wasn't broken...

I'll look at the logs during business hours, I don't have the decoder with me.

Kind regards,

AlbanRampon 09-02-2018 12:03 PM

I pressed send too early.
The reason I'm suggesting this is because your monitor does go out of low power mode as the light goes up.
Gamma is used by Windows for fading to and from black.
You might either have an issue on our gamma implementation or Windows regressed and got a similar bug we observed in Anniversary Update where "default" was wrongly sent as 0... So black. Repluging the monitor makes the dock send a real "default".
Disabling gamma altogether will help narrow down the area.

schmoo 09-02-2018 12:56 PM

Setting "EnableGammaRamp" to false does appear to resolve the issue - the screen does appear to come on with bit of a "flash" which is either:
* Me noticing it since I am looking at it
* I am used to it fading in as a side effect of having the gamma ramp set to true

It sounds like you guys already have a detailed bug report for MS re the "default" v "0" settings, I hope:
* You reopen it
* They listen

Its a shame as f.lux and night light are one of those features that you get used to very quickly!!!

Thx for the quick response - FWIW my new workaround is to shorten my full sleep timeout to match my screen turn off timeout, so I never hit the issue (which I only mention to highlight how much I like the night light feature!!!).

AlbanRampon 09-02-2018 01:58 PM

Thank you for testing.
I'll get a team to look at that and check the issue is really an OS regression and not our bug before submitting a bug report.

Ref 28619 - Black screen when recovering from sleep with gamma & Insiders 17746+

schmoo 09-03-2018 04:29 PM

Should that be: "Black screen when recovering from 'screen auto turn-off' with gamma & Insiders 17746+"

Also in case anyone else lands here you can get the screen to come alive again by manually toggling the night light feature on the settings panel.

Thx for following up...

AlbanRampon 09-03-2018 04:48 PM

As far as I understood from your description, the monitor is still powered and waits for the computer command to wake-up. The monitor does wake up, as the LED goes up, but the screen image is black or the screen is blank. Did I misunderstand?

The reference is for internal purposes, so follow-up is done appropriately by an employee should I go missing or be out, it is using lingo of monitor low power mode, and isn't binding as we are doing the reproduction and, until then, that's only a description of behaviour until parameters are found.
Similarly, if you look at the Windows 10 build number, it is different than the build you are running today...;)

AlbanRampon 09-04-2018 02:00 PM


We have analyzed this and it does not look like an OS regression.
The OS has changed behaviour, but it doesn't behave incorrectly.

I'll comment when I post 9.0 alpha. It handles the default gamma request appropriately.
The root cause was already observed internally and addressed during development.

Kind regards,

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