Thanks for the bug report. It appears your low resolution is due to the radeon kernel driver not being able to detect the monitor's EDID correctly:
[ 5.219380] radeon 0000:01:00.0: DP-1: EDID is invalid: [ 5.219384] [00] ZERO 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 5.219385] [00] ZERO 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 5.219386] [00] ZERO 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 5.219387] [00] ZERO 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 5.219387] [00] ZERO 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 5.219388] [00] ZERO 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 5.219389] [00] ZERO 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 5.219390] [00] ZERO 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 In case this was caused by a hardware change, please try a different DisplayPort cable or even a different monitor. Maybe even try just unplugging it at both ends and plugging it in again. If those don't fix the problem then the next step is to try some older kernel versions so as to try and find the last version in which the bug was not present. You can get all the kernel versions from here: https://kernel.ubuntu.com/~kernel-ppa/mainline/?C=N;O=D ** Package changed: xorg (Ubuntu) => linux (Ubuntu) ** Summary changed: - Radeon issue + Radeon receives invalid EDID (all zeroes) ** Tags added: radeon ** Changed in: linux (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1829915 Title: Radeon receives invalid EDID (all zeroes) Status in linux package in Ubuntu: Incomplete Bug description: I installed ubuntu 18.04 than upgraded to 19.04 and everything was fine(resolution 1920x1080 on a samsung TV) for a few weeks than suddenly it dropped to 1024x768. I'm running a AMD HD7670 video card with a display port to HDMI cable to the tv ProblemType: Bug DistroRelease: Ubuntu 19.04 Package: xorg 1:7.7+19ubuntu12 ProcVersionSignature: Ubuntu 5.0.0-15.16-generic 5.0.6 Uname: Linux 5.0.0-15-generic x86_64 ApportVersion: 2.20.10-0ubuntu27 Architecture: amd64 BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log' CompositorRunning: None CurrentDesktop: ubuntu:GNOME Date: Tue May 21 21:25:49 2019 DistUpgraded: 2019-05-20 01:35:47,157 ERROR got error from PostInstallScript ./xorg_fix_proprietary.py (g-exec-error-quark: Failed to execute child process “./xorg_fix_proprietary.py” (No such file or directory) (8)) DistroCodename: disco DistroVariant: ubuntu ExtraDebuggingInterest: Yes GraphicsCard: Advanced Micro Devices, Inc. [AMD/ATI] Caicos XT [Radeon HD 7470/8470 / R5 235/310 OEM] [1002:6778] (prog-if 00 [VGA controller]) Subsystem: Dell Radeon HD 7470 [1028:2120] InstallationDate: Installed on 2019-05-19 (1 days ago) InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210) MachineType: Dell Inc. OptiPlex 755 ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.0.0-15-generic root=/dev/mapper/ubuntu--vg-root ro quiet splash vt.handoff=1 SourcePackage: xorg UpgradeStatus: Upgraded to disco on 2019-05-19 (1 days ago) dmi.bios.date: 06/11/2012 dmi.bios.vendor: Dell Inc. dmi.bios.version: A22 dmi.board.name: 0PU052 dmi.board.vendor: Dell Inc. dmi.chassis.type: 15 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvrA22:bd06/11/2012:svnDellInc.:pnOptiPlex755:pvr:rvnDellInc.:rn0PU052:rvr:cvnDellInc.:ct15:cvr: dmi.product.name: OptiPlex 755 dmi.sys.vendor: Dell Inc. version.compiz: compiz N/A version.libdrm2: libdrm2 2.4.98+git1905161830.922d92~oibaf~d version.libgl1-mesa-dri: libgl1-mesa-dri 19.2~git1905190730.4689e9~oibaf~d version.libgl1-mesa-glx: libgl1-mesa-glx 19.2~git1905190730.4689e9~oibaf~d version.xserver-xorg-core: xserver-xorg-core 2:1.20.4-1ubuntu3 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.0.1-0ubuntu1 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20180925-2 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1829915/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
