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

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Message-ID: <CADnq5_OoZeFi-VeeMV4AMDxgt+__TmAiN6WE+m0hmYXtmSjx1Q@mail.gmail.com>
Date: Thu, 8 Jan 2026 08:45:12 -0500
From: Alex Deucher <alexdeucher@...il.com>
To: alliancetrooper <alliancetrooper@...ton.me>
Cc: "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>
Subject: Re: External HDMI monitor fails to wake up from DPMS/consoleblank
 since kernel 6.18

On Wed, Jan 7, 2026 at 5:42 PM alliancetrooper
<alliancetrooper@...ton.me> 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.