[Bug 93802] New: [IVB] switching to tty1 causes fifo underrun on pipe B and pipe C (bisected)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=93802

            Bug ID: 93802
           Summary: [IVB] switching to tty1 causes fifo underrun on pipe B
                    and pipe C (bisected)
           Product: DRI
           Version: DRI git
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: chris.bainbridge at gmail.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

Created attachment 121163
  --> https://bugs.freedesktop.org/attachment.cgi?id=121163&action=edit
dmesg with drm.debug

Reproduce: Connect 3 displays, boot to Xorg, press ctrl-alt-f1
Result: fifo underrun, both displays power off

dmesg:

[    9.755511] [drm:intel_check_cpu_fifo_underruns] *ERROR* fifo underrun on
pipe B
[    9.755513] [drm:intel_check_cpu_fifo_underruns] *ERROR* fifo underrun on
pipe C
[    9.755519] [drm:intel_check_pch_fifo_underruns] *ERROR* pch fifo underrun
on pch transcoder B
[    9.755523] [drm:intel_check_pch_fifo_underruns] *ERROR* pch fifo underrun
on pch transcoder C
[    9.761398] [drm:intel_check_cpu_fifo_underruns] *ERROR* fifo underrun on
pipe B
[    9.761400] [drm:intel_check_cpu_fifo_underruns] *ERROR* fifo underrun on
pipe C
[    9.761407] [drm:intel_check_pch_fifo_underruns] *ERROR* pch fifo underrun
on pch transcoder B
[    9.761411] [drm:intel_check_pch_fifo_underruns] *ERROR* pch fifo underrun
on pch transcoder C
[    9.774117] [drm:intel_check_cpu_fifo_underruns] *ERROR* fifo underrun on
pipe C
[    9.774125] [drm:intel_check_pch_fifo_underruns] *ERROR* pch fifo underrun
on pch transcoder C


bisect result (commit was merged in to the Linus tree 3 days ago in
984065055e6e):


92826fcdfc147a7d16766e987c12a9dfe1860c3f is the first bad commit
commit 92826fcdfc147a7d16766e987c12a9dfe1860c3f
Author: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Date:   Thu Dec 3 13:49:13 2015 +0100

    drm/i915: Calculate watermark related members in the crtc_state, v4.

    This removes pre/post_wm_update from intel_crtc->atomic, and
    creates atomic state for it in intel_crtc.

    Changes since v1:
    - Rebase on top of wm changes.
    Changes since v2:
    - Split disable_cxsr into a separate patch.
    Changes since v3:
    - Move some of the changes to intel_wm_need_update.

    Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
    Link:
http://patchwork.freedesktop.org/patch/msgid/56603A49.5000507@linux.intel.com
    Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

:040000 040000 b97b4b2338e1da2ee9e93791154b4deb2ecaf8b6
ae91735a668b6785e55122c646dbca93b54eb8c9 M    drivers

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