[Bug 108656] [CI][BAT bsw] igt at gem_* - fail - Failed assertion: !"GPU hung"

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=108656

Chris Wilson <chris at chris-wilson.co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|REOPENED                    |RESOLVED

--- Comment #17 from Chris Wilson <chris at chris-wilson.co.uk> ---
Step 2:

commit e8894267cc3325901073e8adf0a63e2dc53b6242 (HEAD -> drm-intel-next-queued,
drm-intel/for-linux-next, drm-intel/drm-intel-next-queued)
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Fri Dec 7 09:02:13 2018 +0000

    drm/i915: Pipeline PDP updates for Braswell

    Currently we face a severe problem on Braswell that manifests as invalid
    ppGTT accesses. The code tries to maintain the PDP (page directory
    pointers) inside the context in two ways, direct write into the context
    and a pipelined LRI update. The direct write into the context is
    fundamentally racy as it is unserialised with any access (read or write)
    the GPU is doing. By asserting that Braswell is not used with vGPU
    (currently an unsupported platform) we can eliminate the dangerous
    direct write into the context image and solely use the pipelined update.

    However, the LRI of the PDP fouls up the GPU, causing it to freeze and
    take out the machine with "forcewake ack timeouts". This seems possible
    to workaround by preventing the GPU from sleeping (via means of
    disabling the power-state management interface, i.e. forcing each ring
    to remain awake) around the update. Equally, it seems an EMIT_INVALIDATE
    before the LRI is sufficient to prevent the forcewake errors.

    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108656
    References: https://bugs.freedesktop.org/show_bug.cgi?id=108714
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
    Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
    Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
    Link:
https://patchwork.freedesktop.org/patch/msgid/20181207090213.14352-3-chris@chris-wilson.co.uk


Step 3: Hope for the best.

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