[Bug 101571] [BXT/BSW/GLK] Vulkan tests fail on 4.12 drm-tip

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=101571

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

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

--- Comment #12 from Chris Wilson <chris at chris-wilson.co.uk> ---
commit 686348c782d3247e3bf39fce98d4ac44e147a746
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Fri Jul 21 15:50:37 2017 +0100

    drm/i915: Force CPU synchronisation even if userspace requests ASYNC

    The goal here was to minimise doing any thing or any check inside the
    kernel that was not strictly required. For a userspace that assumes
    complete control over the cache domains, the kernel is usually using
    outdated information and may trigger clflushes where none were
    required.

    However, swapping is a situation where userspace has no knowledge of the
    domain transfer, and will leave the object in the CPU cache. The kernel
    must flush this out to the backing storage prior to use with the GPU. As
    we use an asynchronous task tracked by an implicit fence for this, we
    also need to cancel the ASYNC flag on the object so that the object will
    wait for the clflush to complete before being executed. This also absolves
    userspace of the responsibility imposed by commit 77ae9957897d ("drm/i915:
    Enable userspace to opt-out of implicit fencing") that its needed to ensure
    that the object was out of the CPU cache prior to use on the GPU.

    Fixes: 77ae9957897d ("drm/i915: Enable userspace to opt-out of implicit
fencing")
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101571
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
    Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
    Cc: Jason Ekstrand <jason at jlekstrand.net>
    Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
    Link:
https://patchwork.freedesktop.org/patch/msgid/20170721145037.25105-5-chris@chris-wilson.co.uk
    Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

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