On Thu, May 21, 2015 at 09:11:04 +0200, Cesare Leonardi wrote: > Package: src:linux > Version: 4.0.2-1 > Severity: normal > > Since kernel version 4.0 (also the previous 4.0.0-trunk from > experimental) if i try to switch to a VT from an X session (also from > the login manager), the screen becomes black and i'm not able to > recover from that situation, neither for the X session. > That's always reproducible and i wasn't able to find a workaround. > > After that you can observe: > - the system is not freezed and you can work blindly. > - the display shows no output but is powered on: the backlight is on and > i can change its brightness. > > After a reboot, looking in the log i always find two message like those: > ----- > mag 21 07:35:40 etna kernel: [drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR* uncleared fifo underrun on pipe A > mag 21 07:35:40 etna kernel: [drm:ironlake_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun > ----- > > So it looks like an Intel specific bug. > This is an Asuspro PU301LS notebook, with Haswell i7 4500U and HD4400. > > I had suspected for the "acpi_osi=" kernel parameter that i use to make > the backlight works properly, but i found that removing it makes no > difference. > > Note also that if i don't try to switch to a VT, i'm able to works > apparently without problems, like now while i'm writing this bug. > Please file this upstream at https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel See instructions at https://01.org/linuxgraphics/documentation/development/how-report-bugs Thanks, Julien
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