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/[email protected] > > 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 <[email protected]> > Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4780 > Reviewed-by: Chris Park <[email protected]> > Signed-off-by: Mario Limonciello <[email protected]> > Signed-off-by: Matthew Stewart <[email protected]> > Tested-by: Dan Wheeler <[email protected]> > Signed-off-by: Alex Deucher <[email protected]> > (cherry picked from commit ac1e65d8ade46c09fb184579b81acadf36dcb91e) > Cc: [email protected] > Signed-off-by: Greg Kroah-Hartman <[email protected]> > > Does this ring any bell? > > #regzbot introduced: ae5b1d291c814a2884c3d54a56e83bc99052b1eb > #regzbot link: https://bugs.debian.org/1139950 > > Regards, > Salvatore
