[regression] amdgpu carrizo: no display signal after modeset

[regression] amdgpu carrizo: no display signal after modeset

[Salvatore Bonaccorso]

Control: forwarded -1 https://lore.kernel.org/regressions/178198613176.3658222.16247101620976737948@eldamar.lan

Hi

Jaak Ristioja reported the following issue in Debian at
https://bugs.debian.org/1139950 . Part of the original report contains
Debian specific version information, but Jaak did as well a bisecion
for the regression see below:

On Sun, Jun 14, 2026 at 02:27:01AM +0300, Jaak Ristioja wrote:
> Package: linux-modules-7.0.10+deb13-amd64
> Version: 7.0.10-1~bpo13+1
> 
> Hi,
> 
> Upgrading (after a long while) Debian Trixie installations on two different
> HP EliteDesk 705 G4 DM 35W computers with AMD PRO A10-9700E R7 (carrizo)
> resulted in both machines blanking the screen right after kernel modesetting
> activates via amdgpu, with the monitor reporting "no signal". There are no
> other symptoms besides losing the display as the system continues to run and
> is accessible using keyboard and network.
> 
> Bug first discovered with stable kernel linux-image-6.12.90+deb13.1-amd64
> (6.12.90-2) and the one from trixie-backports. The device is connected to a
> monitor using a DisplayPort to HDMI adapter. The bug occurs regardless of
> which if the two available physical DisplayPort ports to use.
> 
> I don't remember this being an issue some months ago, so I tried to
> reproduce this booting the Debian 13.1.0 and 13.4.0 install DVD images and
> using the kernel modules/firmware therein:
> 
>   13.1.0 installer:
>     firmware-amd-graphics_20250410-2
>     linux-image-6.12.43+deb13-amd64_6.12.43-1
>   13.4.0 installer:
>     firmware-amd-graphics 20250410-2
>     linux-image-6.12.73+deb13-amd64_6.12.73-1
> 
> I essentially unpacked the two *.deb files manually, depmod -a; modprobe drm
> debug=0x1ff; modprobe amdgpu.
> 
> I observed the bug reproduce using the 13.4.0 installer, but not on the
> 13.1.0 installer, meaning this is a regression somewhere between kernel
> versions 6.12.43-1 and 6.12.73-1.

The reporter did a bisection and found as offending commit:

    drm/amd/display: Bump the HDMI clock to 340MHz

    commit fee50077656d8a58011f13bca48f743d1b6d6015 upstream.

    [Why]
    DP-HDMI dongles can execeed bandwidth requirements on high resolution
    monitors. This can lead to pruning the high resolution modes.

    HDMI 1.3 bumped the clock to 340MHz, but display code never matched it.

    [How]
    Set default to (DVI) 165MHz.  Once HDMI display is identified update
    to 340MHz.

    Reported-by: Dianne Skoll <dianne@skoll.ca>
    Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4780
    Reviewed-by: Chris Park <chris.park@amd.com>
    Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
    Signed-off-by: Matthew Stewart <matthew.stewart2@amd.com>
    Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
    (cherry picked from commit ac1e65d8ade46c09fb184579b81acadf36dcb91e)
    Cc: stable@vger.kernel.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Does this ring any bell?

#regzbot introduced: ae5b1d291c814a2884c3d54a56e83bc99052b1eb
#regzbot link: https://bugs.debian.org/1139950

Regards,
Salvatore

Re: [resend] [regression] amdgpu carrizo: no display signal after modeset

[Salvatore Bonaccorso]

Hi

Resending because of typ in mailing list address.

On Sat, Jun 20, 2026 at 10:11:25PM +0200, Salvatore Bonaccorso wrote:
> Control: forwarded -1 https://lore.kernel.org/regressions/178198613176.3658222.16247101620976737948@eldamar.lan
> 
> Hi
> 
> Jaak Ristioja reported the following issue in Debian at
> https://bugs.debian.org/1139950 . Part of the original report contains
> Debian specific version information, but Jaak did as well a bisecion
> for the regression see below:
> 
> On Sun, Jun 14, 2026 at 02:27:01AM +0300, Jaak Ristioja wrote:
> > Package: linux-modules-7.0.10+deb13-amd64
> > Version: 7.0.10-1~bpo13+1
> > 
> > Hi,
> > 
> > Upgrading (after a long while) Debian Trixie installations on two different
> > HP EliteDesk 705 G4 DM 35W computers with AMD PRO A10-9700E R7 (carrizo)
> > resulted in both machines blanking the screen right after kernel modesetting
> > activates via amdgpu, with the monitor reporting "no signal". There are no
> > other symptoms besides losing the display as the system continues to run and
> > is accessible using keyboard and network.
> > 
> > Bug first discovered with stable kernel linux-image-6.12.90+deb13.1-amd64
> > (6.12.90-2) and the one from trixie-backports. The device is connected to a
> > monitor using a DisplayPort to HDMI adapter. The bug occurs regardless of
> > which if the two available physical DisplayPort ports to use.
> > 
> > I don't remember this being an issue some months ago, so I tried to
> > reproduce this booting the Debian 13.1.0 and 13.4.0 install DVD images and
> > using the kernel modules/firmware therein:
> > 
> >   13.1.0 installer:
> >     firmware-amd-graphics_20250410-2
> >     linux-image-6.12.43+deb13-amd64_6.12.43-1
> >   13.4.0 installer:
> >     firmware-amd-graphics 20250410-2
> >     linux-image-6.12.73+deb13-amd64_6.12.73-1
> > 
> > I essentially unpacked the two *.deb files manually, depmod -a; modprobe drm
> > debug=0x1ff; modprobe amdgpu.
> > 
> > I observed the bug reproduce using the 13.4.0 installer, but not on the
> > 13.1.0 installer, meaning this is a regression somewhere between kernel
> > versions 6.12.43-1 and 6.12.73-1.
> 
> The reporter did a bisection and found as offending commit:
> 
>     drm/amd/display: Bump the HDMI clock to 340MHz
> 
>     commit fee50077656d8a58011f13bca48f743d1b6d6015 upstream.
> 
>     [Why]
>     DP-HDMI dongles can execeed bandwidth requirements on high resolution
>     monitors. This can lead to pruning the high resolution modes.
> 
>     HDMI 1.3 bumped the clock to 340MHz, but display code never matched it.
> 
>     [How]
>     Set default to (DVI) 165MHz.  Once HDMI display is identified update
>     to 340MHz.
> 
>     Reported-by: Dianne Skoll <dianne@skoll.ca>
>     Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4780
>     Reviewed-by: Chris Park <chris.park@amd.com>
>     Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>     Signed-off-by: Matthew Stewart <matthew.stewart2@amd.com>
>     Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
>     Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
>     (cherry picked from commit ac1e65d8ade46c09fb184579b81acadf36dcb91e)
>     Cc: stable@vger.kernel.org
>     Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> Does this ring any bell?
> 
> #regzbot introduced: ae5b1d291c814a2884c3d54a56e83bc99052b1eb
> #regzbot link: https://bugs.debian.org/1139950
> 
> Regards,
> Salvatore

Re: [resend] [regression] amdgpu carrizo: no display signal after modeset

[Mario Limonciello]

There have been other bandwith related changes.
Would you mind please trying to reproduce on more recent mainline 
release, IE 7.1.y?

Also; can you please check both your cable and dongle?  I wonder if one 
of them is not compatible with HDMI 1.3?  Are they marketed as 
"Standard" or "High Speed"?

Re: [resend] [regression] amdgpu carrizo: no display signal after modeset

[Jaak Ristioja]

[-- Attachment #1: Type: text/plain, Size: 525 bytes --]

Issue also seems to occurs with 7.1.1 (`dmesg -f kern` output attached).

The DisplayPort to HDMI dongle does not have markings on the body to 
identify the exact model, but by the looks of it I think it might be a 
Vention HBKB0, which seems to be marketed as "1080p@60", "DP male to 
HDMI female", "classic" (as opposed to "4K"). According to some 
materials, the chip inside is a MXP3361.

The text on the HDMI cable reads "ULTRA HIGH SPEED HDMI™ CABLE - 
WWW.HAMA.COM - HAMA GMBH & CO KG 86652 MONHEIM/GERMANY - 82623".

[-- Attachment #2: dmesg-7.1.1.txt.xz --]
[-- Type: application/x-xz, Size: 221080 bytes --]

Re: [resend] [regression] amdgpu carrizo: no display signal after modeset

[Jaak Ristioja]

On 2026.06.22 16:52, Jaak Ristioja wrote:
> Issue also seems to occurs with 7.1.1 (`dmesg -f kern` output attached).
> 
> The DisplayPort to HDMI dongle does not have markings on the body to 
> identify the exact model, but by the looks of it I think it might be a 
> Vention HBKB0, which seems to be marketed as "1080p@60", "DP male to 
> HDMI female", "classic" (as opposed to "4K"). According to some 
> materials, the chip inside is a MXP3361.
> 
> The text on the HDMI cable reads "ULTRA HIGH SPEED HDMI™ CABLE - 
> WWW.HAMA.COM - HAMA GMBH & CO KG 86652 MONHEIM/GERMANY - 82623".

Reverting commit fee50077656 ("drm/amd/display: Bump the HDMI clock to 
340MHz") on top of v7.1.1 appears to resolve the issue, as I am now able 
to get a picture.


PS: My previous e-mail with the attached dmesg-7.1.1.txt.xz file was 
bounced from @amd.com addresses: Diagnostic-Code: smtp;550 5.0.350 One 
or more of the attachments in your email is of a file type that is NOT 
allowed by the recipient's organization.

Re: [resend] [regression] amdgpu carrizo: no display signal after modeset

[Dianne Skoll]

On Mon, 22 Jun 2026 20:46:44 +0300
Jaak Ristioja <jaak@ristioja.ee> wrote:

> Reverting commit fee50077656 ("drm/amd/display: Bump the HDMI clock to 
> 340MHz") on top of v7.1.1 appears to resolve the issue, as I am now able 
> to get a picture.

Unfortunately, reverting that commit will *break* it for me with my Dasung
E-Ink monitor. :(

If it's not possible to detect what the maximum HDMI clock should be, perhaps
a module parameter specifying the HDMI version could be implemented?  Or
a parameter to specify the maximum HDMI clock directly?

Regards,

Dianne.

Re: [resend] [regression] amdgpu carrizo: no display signal after modeset

[Thorsten Leemhuis]

On 6/22/26 21:34, Dianne Skoll wrote:
> On Mon, 22 Jun 2026 20:46:44 +0300
> Jaak Ristioja <jaak@ristioja.ee> wrote:
> 
>> Reverting commit fee50077656 ("drm/amd/display: Bump the HDMI clock to 
>> 340MHz") on top of v7.1.1 appears to resolve the issue, as I am now able 
>> to get a picture.
> 
> Unfortunately, reverting that commit will *break* it for me with my Dasung
> E-Ink monitor. :(
Jaak, was this ever resolved? It looks like this fell through the
cracks, but maybe I missed something.

If this is still unfixed, I think it likely is best if you report this
to https://gitlab.freedesktop.org/drm/amd/-/work_items/ if you haven't
done so already -- I suspect that is more likely to get the attention of
the amdgpu maintainers. Please drop the link to the ticket here after
submitting the issue.

Ciao, Thorsten