I still believe that this bug is present since initial implementation of DRRS (kernels 4.0 and 4.1). For now I have to disable DRRS by default with a patch. Updated version in attachment.
** Patch added: "Patch for 5.13 and 5.14" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1928138/+attachment/5525692/+files/i915---disable_drrs_by_default_5-13.patch -- 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/1928138 Title: Flickering on built-in display (Intel Haswell graphics) since kernel v4.1 [bisected and workaround attached] Status in Linux: Unknown Status in linux package in Ubuntu: New Bug description: Since kernel 4.1 laptop HP Elitebook Folio 1040 G1 (with Intel i5-4210U) has a pretty serious issue with flickering Symptoms: 1) If I leave mouse cursor for a few seconds, then start moving it, there's a slight flicker (like display brightness changes a bit). There's also some flickering even without user interactions. 2) On the top left corner sometimes appears artifacts. It's relatively easy to see with black window decorations on top of the screen. This one is showed at the attached video bellow 3) With kernel boot options drm.debug=0x1e log_buf_len=4M dmesg shows constant refresh rate changes (even if it's set to 40HZ) [ 29.977378] [drm:intel_dp_set_drrs_state [i915]] eDP Refresh Rate set to : 40Hz [ 30.456537] [drm:intel_dp_set_drrs_state [i915]] eDP Refresh Rate set to : 60Hz [ 33.973392] [drm:intel_dp_set_drrs_state [i915]] eDP Refresh Rate set to : 40Hz [ 35.055923] [drm:intel_dp_set_drrs_state [i915]] eDP Refresh Rate set to : 60Hz nomodeset boot option eliminates flickering Turns out Display Refresh Rate Switching (DRRS) feature doesn't work correctly here. It was implemented on kernels 4.0...4.1 but on a particular machine flickering started with 4.1. As a workaround I'm attaching a patch which disables DRRS by default and adds module parameter "enable_drrs" to activate it. It's made for kernel 5.12 and should work for older versions as well (tested with 5.11). Until this issue is resolved, please consider adding parameter to disable DRRS. Windows has such option on Intel® Graphics Command Center. To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1928138/+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
