[Bug 92187] New: check_crtc_state mismatch in ips_enabled on 4.2.1-1

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=92187

            Bug ID: 92187
           Summary: check_crtc_state mismatch in ips_enabled on 4.2.1-1
           Product: DRI
           Version: unspecified
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: me at hkjn.me
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

Created attachment 118530
  --> https://bugs.freedesktop.org/attachment.cgi?id=118530&action=edit
i915 call trace from kernel

Version of i915 (`pacman -Qi xf86-video-intel`): 1:2.99.917+381+g5772556-1
System architecture (`uname -m`): x86_64
Kernel version (`uname -r`): 4.2.1-1-ARCH
Linux distribution: Arch Linux
Machine: Lenovo Thinkpad X240
Display connector: VGA

After upgrading the Linux kernel yesterday, I noticed a delay when my laptop
was resuming from hibernation. When looking at kernel logs, there was a i915
call trace from the kernel (see attachment) saying "mismatch in ips_enabled
(expected 1, found 0)".

The graphics did recover after waiting ~10 sec or so, but I also noticed that
my external monitor didn't get the mirrored image of my laptop, as it usually
does. Closing the lid and opening it again fixed the issue with the external
monitor (and I can't be sure it was caused by this issue).

The issue did not seem to be present on the previous version of the kernel I
was running, 4.0.5-1-ARCH, but searching through kernel logs it's appeared six
times since when I upgraded the kernel yesterday, often but not always
associated with putting the laptop into hibernation.

Let me know how to provide more info, sorry about not having a full set of
steps to repro the issue yet.

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