Re: External HDMI monitor fails to wake up from DPMS/consoleblank since kernel 6.18

[Alex Deucher]

On Wed, Jan 7, 2026 at 5:42 PM alliancetrooper
<alliancetrooper@xxxxxxxxx> wrote:
>
> Hello.
>
> I am reporting a regression in the kernel. an external HDMI monitor fails to wake up from a low-power state.
> The issue occurs both in the VT console (using consoleblank parameter) and in the X.Org graphical session (using xset dpms force off).
> The internal laptop display resumes correctly. This problem was not present in Linux kernel 6.17. It started occurring after updating to kernel 6.18.0.

Please file a ticket at:
https://gitlab.freedesktop.org/drm/amd/-/issues

Can you bisect?

Thanks,

Alex

> My Kernel: 6.18.3, built from vanilla sources in Gentoo. Display controller: Advanced Micro Devices, Inc. [AMD/ATI] Strix [Radeon 880M / 890M] (rev c4).
>
> No messages in dmesg regarding this.
>
> Steps to Reproduce:
> 1.  Connect an external monitor via HDMI.
> 2.  Boot with the kernel parameter consoleblank=30.
> 3.  Wait 30 seconds for the screen to blank and some time (no more than 5 mins) additionally.
> 4.  Try to wake the display by pressing a key. The external monitor remains off, while the internal laptop display turns on.
> 5.  Also reproducible in X11/Xorg session using xset dpms force off. It is also needed to spent some time in off state.
>
> Thank you.