[Bug 107543] New: Video cutout on Kaby Lake U processors.

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=107543

            Bug ID: 107543
           Summary: Video cutout on Kaby Lake U processors.
           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: phil.smith at adder.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

We have been looking at 2 devices, one with i3-7100U and one with Celeron
3965U,  and both will occasionally stop displaying video entirely (but will
still be running, i.e. ping-able, can SSH to them etc...) when running our CPU
heavy code or even just sitting at the (Wayland or X.org) desktop. It seems to
occur more frequently when the system is under high CPU/GPU load. We believe
the error is:

[drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO
underrun

The error manifests itself sometimes within minutes of booting, other times
within hours and sometimes within days.

We are running Debian stable (stretch 9.5) and have tried the default kernel
(4.9.0-6-amd64) and the latest kernel from backports (4.16.0-0.bpo.1-amd64 and
4.17.0-0.bpo.1-amd64).

Things we have tried:
- Updating to the latest DMC firmware:
$ ls -l /lib/firmware/i915/kbl_dmc*
lrwxrwxrwx 1 root root   19 Aug  7 17:49 /lib/firmware/i915/kbl_dmc_ver1.bin ->
kbl_dmc_ver1_04.bin
-rw-r--r-- 1 root root 8840 Aug  7 17:49 /lib/firmware/i915/kbl_dmc_ver1_04.bin
$ md5sum /lib/firmware/i915/kbl_dmc*
924d401952828c04fce352291559a1e0  /lib/firmware/i915/kbl_dmc_ver1.bin
924d401952828c04fce352291559a1e0  /lib/firmware/i915/kbl_dmc_ver1_04.bin
- Booting with 'intel_iommu=off'.
- Booting with 'i915.enable_fbc=0'. Anecdotally, this seems to improve the
issue but not resolve it.

Rebooting either device resolves the issue.

Intel Premier Support has redirected us to post a bug report here.

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