Thanks for the details and video. I've only ever seen G-SYNC on a Windows machine, in which case the display would blank whenever G-SYNC was enabled, just like you describe. So if the same happens in both Windows and Linux then maybe it's not a bug?...
If you didn't see the blanking in the past then that might just indicate that no switching was occurring. Perhaps the monitor was either permanently in, or never in, G-SYNC mode. If the driver needs to blank the screen for a second or two to switch modes then I'm not sure that's a bug. You should probably ask in https://forums.developer.nvidia.com/c/gpu-graphics/linux/148 or a similar forum. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to nvidia-graphics-drivers-470 in Ubuntu. https://bugs.launchpad.net/bugs/1950720 Title: GSYNC bug regression in 495.44 Ubuntu 21.10 Status in nvidia-graphics-drivers-470 package in Ubuntu: Confirmed Status in nvidia-graphics-drivers-495 package in Ubuntu: Confirmed Bug description: [ Description ] Video of signal loss with flipping enabled: https://youtu.be/V5DGcHN- BJs In NVIDIA the 495 driver for Ubuntu 21.10, with G-SYNC enabled in OpenGL Settings of NVIDIA Settings, the G-SYNC compatible monitor loses sync momentarily (1~2 seconds) when switching to GPU accelerated application. Examples of this are: - When launching a game full-screen - Launching a GPU accelerated game in Window mode - Launching Steam - Launching kitty terminal https://sw.kovidgoyal.net/kitty/ This issue happens at all refresh rates: 60 Hz, 120 Hz, 144 Hz and 165 Hz. Note: This example doesn't explicitly show G-SYNC being enabled in the onscreen indicator, rather what happens when G-SYNC is enabled in the settings. If I disable G-SYNC, but leave flipping enabled, the issue is not present. If I enabled G-SYNC, but disable flipping, the issue is not present. If both are enabled, then the issue occurs. [ Hardware ] - NVIDIA GeForce RTX 2080 Super - Dell 27" S2721DGF G-Sync Compatible monitor - High quality DisplayPort cable [ Settings ] In the NVIDIA OpenGL settings, the following settings are enabled: - Sync to VBlank Enabled - Allow Flipping Enabled - Image Setting: High Performance - Allow G-SYNC-/G-SYNC Compatible Enabled - Use Conformant Texture Clamping Enabled [ Observations ] When I disable Allow Flipping, the issue goes away. No signal is lost when changing to different GPU accelerated applications. Sometimes there is a brief flicker when opening a GPU accelerated program with flipping disabled, but it's not a signal loss, rather a very fast momentary flick of the display, but it's does not impact usability. As flipping is required for G-SYNC to function, therefore losing the benefit of G-SYNC if I were to disable flipping. [ Correlation to previous bug ] This issue was present in Ubuntu 21.04, eventually driver 495.44 resolved this problem on the 5.14.1 kernel. I will add that when I first had this machine and screen in 20.10 and 21.04, it was not experiencing the signal loss issue. The bug described in the change log in this launchpad bug seems to reference the type of regression I am experiencing https://launchpad.net/bugs/1950665. [ Troubleshooting ] Full driver purges between trying different drivers: - Tried downgrading to 470.82 - Went back to the standard kernel for 21.10 (5.13.0-21-generic) at the time - Tried deleting ~/.nv, ~/.cache/nvidia - Reverted to previous X11 conf - Tried 5.14.1 which was working in Ubuntu 21.04 - Tried kernels 5.14.17, 5.15.6 - Persists in 470.94 (NVIDIA bundle and Graphics Drivers PPA) - Persists in 495.46 (NVIDIA bundle and Graphics Drivers PPA) - Persists in 510.39.01 (NVIDIA bundle) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-470/+bug/1950720/+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
