Created attachment 122497 Cache DP signal levels In your case, when DP link is retrained with the settings from previous link training the clock recovery fails. This leads into a situation where link training is started from scratch. However, now the clock recovery seems to be happy with the lower voltage swing and pre-emphasis settings than with the first iteration round. You may experience flickering due to this as the physical link may require higher voltage swing or pre-emphasis than provided.
We could try the following trick here. Let's cache the signal levels and in case of link retraining we retrain the link until we have reached the previously trained signal levels and clock recovery is reached. Please, give this a go on top of the latest drm-intel-nightly with these 3 patches applied. Dmesg logs are appreciated too ;) -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xserver-xorg-video-intel in Ubuntu. https://bugs.launchpad.net/bugs/1522922 Title: Screen flickering in Intel i915 driver Status in Nouveau Xorg driver: Incomplete Status in xserver-xorg-video-intel package in Ubuntu: Triaged Bug description: There's an upstream bug reported here https://bugs.freedesktop.org/show_bug.cgi?id=91393 that causes screen flickering when using the Intel i915 builtin driver (at resolutions lower than the maximal one). I think that it will be fixed in newer kernel versions, but for the time being, as reported here https://bugs.freedesktop.org/show_bug.cgi?id=91393#c25 (and as personally tested) reverting those two commits fixes the problem. Would that be possible to release a fixed version for the 4.2.0 stream? ProblemType: Bug DistroRelease: Ubuntu 15.10 Package: linux-image-4.2.0-19-generic 4.2.0-19.23 ProcVersionSignature: Ubuntu 4.2.0-19.23-generic 4.2.6 Uname: Linux 4.2.0-19-generic x86_64 ApportVersion: 2.19.1-0ubuntu5 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: bettini 1378 F.... pulseaudio /dev/snd/controlC1: bettini 1378 F.... pulseaudio CurrentDesktop: KDE Date: Fri Dec 4 19:01:00 2015 HibernationDevice: RESUME=UUID=7ddbc972-3ad6-40de-9313-2bb9395145f9 InstallationDate: Installed on 2015-05-08 (210 days ago) InstallationMedia: Kubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422) MachineType: Dell Inc. Dell Precision M3800 ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-19-generic root=UUID=dd2c7064-53b9-4720-96ab-5e8a3f2db3ea ro noprompt quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-4.2.0-19-generic N/A linux-backports-modules-4.2.0-19-generic N/A linux-firmware 1.149.3 SourcePackage: linux UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev' UpgradeStatus: Upgraded to wily on 2015-11-07 (26 days ago) dmi.bios.date: 08/17/2015 dmi.bios.vendor: Dell Inc. dmi.bios.version: A10 dmi.board.name: Dell Precision M3800 dmi.board.vendor: Dell Inc. dmi.board.version: A10 dmi.chassis.type: 8 dmi.chassis.vendor: Dell Inc. dmi.chassis.version: Not Specified dmi.modalias: dmi:bvnDellInc.:bvrA10:bd08/17/2015:svnDellInc.:pnDellPrecisionM3800:pvrA10:rvnDellInc.:rnDellPrecisionM3800:rvrA10:cvnDellInc.:ct8:cvrNotSpecified: dmi.product.name: Dell Precision M3800 dmi.product.version: A10 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/nouveau/+bug/1522922/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
