Had it happen today for the first time. Other than Ubuntu updates no changes to the configuration in months so it seems to be a very recent change. The last time I used the dual monitor config was 5 days ago, with no troubles at all. Now the 2nd monitor (4k) goes blank and comes back about every 5 seconds. Tried resetting display resolution (and then back again) and may have helped for now.
Latest Dell XPS13 dev edition running Ubuntu 15.04. uname Linux crom 3.19.0-33-generic #38-Ubuntu SMP Fri Nov 6 18:18:12 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux dmesg [27734.104083] [drm:gen8_irq_handler [i915_bpo]] *ERROR* The master control interrupt lied (SDE)! (many times) lspci 00:00.0 Host bridge: Intel Corporation Broadwell-U Host Bridge -OPI (rev 09) 00:02.0 VGA compatible controller: Intel Corporation Broadwell-U Integrated Graphics (rev 09) 00:03.0 Audio device: Intel Corporation Broadwell-U Audio Controller (rev 09) 00:04.0 Signal processing controller: Intel Corporation Broadwell-U Camarillo Device (rev 09) 00:14.0 USB controller: Intel Corporation Wildcat Point-LP USB xHCI Controller (rev 03) 00:16.0 Communication controller: Intel Corporation Wildcat Point-LP MEI Controller #1 (rev 03) 00:1b.0 Audio device: Intel Corporation Wildcat Point-LP High Definition Audio Controller (rev 03) 00:1c.0 PCI bridge: Intel Corporation Wildcat Point-LP PCI Express Root Port #1 (rev e3) 00:1c.3 PCI bridge: Intel Corporation Wildcat Point-LP PCI Express Root Port #4 (rev e3) 00:1d.0 USB controller: Intel Corporation Wildcat Point-LP USB EHCI Controller (rev 03) 00:1f.0 ISA bridge: Intel Corporation Wildcat Point-LP LPC Controller (rev 03) 00:1f.2 SATA controller: Intel Corporation Wildcat Point-LP SATA Controller [AHCI Mode] (rev 03) 00:1f.3 SMBus: Intel Corporation Wildcat Point-LP SMBus Controller (rev 03) 00:1f.6 Signal processing controller: Intel Corporation Wildcat Point-LP Thermal Management Controller (rev 03) 01:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5249 PCI Express Card Reader (rev 01) 02:00.0 Network controller: Broadcom Corporation BCM4352 802.11ac Wireless Network Adapter (rev 03) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1488719 Title: dmesg shows "[drm:gen8_irq_handler [i915]] *ERROR* The master control interrupt lied (SDE)!" To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1488719/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs