Source: linux Version: 4.0.8-1 Severity: important On my thinkpad T440s (Intel graphics), I often use an external (HDMI) monitor via a docking station. With the 3.16.7-ckt11 version of the kernel, this works great. With 4.0.8-1 (current in testing), it doesn't work at all -- it detects that the monitor is there, Xorg.0.log says:
[ 103.360] (II) intel(0): switch to mode 3440x1440@60.0 on DP2-1 using pipe 1, position (1920, 0), rotation normal, reflection none [ 104.092] (II) intel(0): switch to mode 1920x1080@60.0 on eDP1 using pipe 0, position (0, 0), rotation normal, reflection none but then the kernel log says: Jul 17 17:10:21 branna kernel: [ 13.488687] [drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR* uncleared fifo underrun on pipe A Jul 17 17:10:21 branna kernel: [ 13.488707] [drm:ironlake_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun and the external monitor stays resolutely blank. The gnome display settings tool thinks that it's active, and that it can be configured; each time I try reconfiguring it I get the fifo underrun error again. But at no point does the external monitor leave power-saving mode. Curiously, if I switch to a text console (ctrl-alt-f1), then the text console *does* appear on both the built-in and external displays. The cause is definitely the kernel, because if I reboot and select the older kernel from the grub menu, while keeping everything else the same, then it works perfectly again. -- System Information: Debian Release: stretch/sid APT prefers testing APT policy: (900, 'testing'), (500, 'unstable') Architecture: amd64 (x86_64) Foreign Architectures: i386 Kernel: Linux 3.16.0-4-amd64 (SMP w/4 CPU cores) Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Init: systemd (via /run/systemd/system) -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
