linux-kernel - Re: [REGRESSION] Black screen on HDMI power-cycle after commit 3471b9a31ce3 (7900XTX + LG C3)

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Message-ID: <CABXGCsPcKwL9MJe32QtTDARpMsJ9pxHxo0nSGTu9KkXmMQ_H+Q@mail.gmail.com>
Date: Mon, 8 Dec 2025 21:53:36 +0500
From: Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
To: "Pillai, Aurabindo" <Aurabindo.Pillai@....com>, amd-gfx list <amd-gfx@...ts.freedesktop.org>, 
	Linux List Kernel Mailing <linux-kernel@...r.kernel.org>
Cc: "Vojvodic, Relja (Reggie)" <Relja.Vojvodic@....com>, "Liu, Wenjing" <Wenjing.Liu@....com>, 
	"Deucher, Alexander" <Alexander.Deucher@....com>
Subject: Re: [REGRESSION] Black screen on HDMI power-cycle after commit
 3471b9a31ce3 (7900XTX + LG C3)

On Mon, Dec 8, 2025 at 8:46 PM Pillai, Aurabindo
<Aurabindo.Pillai@....com> wrote:
>
> [AMD Official Use Only - AMD Internal Distribution Only]
>
> Hi Mikhail,
>
> The log you uploaded is a little too long, and has quite a few errors, which makes it hard to pinpoint the errors that are of interest to us. Could you please drm.debug=0x116 to kernel cmdline, run "sudo dmesg -C" to clear all the logs, then perform the hotplug, and capture the dmesg log?
>
> Looking at the regression patch, there are two new hunks that change the early return logic, which is causing the regression. Could you check if you need both the hunks removed for fixing the issue, or only one of those hunks ?

Hi Aurabindo,

Regarding your question about the hunks: I have so far only tested a
full revert of commit 3471b9a31ce3, which fixes the issue.

I will perform additional tests to verify if reverting only one of the
hunks (either in read_scdc_caps or write_scdc_data) is sufficient to
resolve the regression, and I will get back to you with the results.

The attached dmesg.zip contains the log captured with drm.debug=0x116
as requested.

-- 
Best Regards,
Mike Gavrilov.

Download attachment "dmesg.zip" of type "application/zip" (13350 bytes)