At work I recently bought a new primary monitor for my laptop's external dual-screen setup. After a bit of research it turned out I need to connect it in a daisy-chain DisplayPort setup, otherwise the resolution of my older second screen would be limited to 1024x768. As soon as figured out what I needed to do and I set everything up, all the monitors started working in their native resolution, but the external screens started to randomly turn black for like half a second, but not both at the same time, then again work well for a while until the next half-second blackout. With the same kernel, the same monitors as well as the previous monitors configured to use both my video outputs didn't have this flockering issue, nor did I see it on the other external monitor that I connect at home. These are my system specs: OS: Ubuntu Xenial x86_64 Kernel: 4.7.0-040700rc5-lowlatency from http://kernel.ubuntu.com/~kernel-ppa/mainline/, installed before because of a similar bug #95176, which used to manifest on my laptop's screen. lspci output: 00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 0b) 00:03.0 Audio device: Intel Corporation Haswell-ULT HD Audio Controller (rev 0b) 00:14.0 USB controller: Intel Corporation 8 Series USB xHCI HC (rev 04) 00:16.0 Communication controller: Intel Corporation 8 Series HECI #0 (rev 04) 00:16.3 Serial controller: Intel Corporation 8 Series HECI KT (rev 04) 00:19.0 Ethernet controller: Intel Corporation Ethernet Connection I218-LM (rev 04) 00:1b.0 Audio device: Intel Corporation 8 Series HD Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 1 (rev e4) 00:1c.3 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 4 (rev e4) 00:1c.4 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 5 (rev e4) 00:1d.0 USB controller: Intel Corporation 8 Series USB EHCI #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation 8 Series LPC Controller (rev 04) 00:1f.2 SATA controller: Intel Corporation 8 Series SATA Controller 1 [AHCI mode] (rev 04) 00:1f.3 SMBus: Intel Corporation 8 Series SMBus Controller (rev 04) 02:00.0 Network controller: Intel Corporation Wireless 7260 (rev 73) 03:00.0 SD Host controller: O2 Micro, Inc. SD/MMC Card Reader Controller (rev 01) The dmesg output doesn't show any messages related to the intel driver, so that's why I didn't attach it, but if this information is not enough I can produce more logs upon request.
I was trying to reproduce this issue with latest kernel. 4.10.0 over Ubuntu 16.10, and i'm not facing this problem. Could you provide your xorg.log and dmesg? By the way, are you facing this issue trying to reach 4K resolution? (Please provide output from xrandr --verbose as well.)
(In reply to Elio from comment #1) > I was trying to reproduce this issue with latest kernel. 4.10.0 over Ubuntu > 16.10, and i'm not facing this problem. Could you provide your xorg.log and > dmesg? By the way, are you facing this issue trying to reach 4K resolution? > (Please provide output from xrandr --verbose as well.) For drm dmesg, please always add, or ask to add, drm.debug=14 module parameter. The value is a bit mask, so other values may be relevant depending on the case, but 14 should be fine here.
Reporter, is this issue still valid. Can you respond?
Yes as far as I can tell it still happens even with 4.11 but I got sick of it and as a workaround I am no longer using a daisy chain but two dedicated DP ports and this way it's not flickering anymore.
I forgot to mention that this is likely not an Intel driver issue but a common hardware of firmware problem with the Synaptics hub used for the docking station on Dell laptops: https://community.spiceworks.com/topic/893931-e5450-docking-issues?page=3#entry-4739894 I still had this even with the latest available firmware and BIOS, and I initially thought it may be an Intel driver issue, but apparently it's not.
The user Cristian Magherusan-Stanciu, believe as same as us, that the issue could be an issue with hardware configuration and not with software configuration.
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