[Bug 100587] [CI]gem_mmap_gtt/coherency failing assertion cpu[x] == i

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=100587

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|WONTFIX                     |FIXED
             Status|CLOSED                      |RESOLVED

--- Comment #26 from Chris Wilson <chris at chris-wilson.co.uk> ---
kernel commit 900ccf30f9e112b508a61b228bf014e3bea14bc4 (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 Jul 20 11:19:10 2018 +0100

    drm/i915: Only force GGTT coherency w/a on required chipsets

    Not all chipsets have an internal buffer delaying the visibility of
    writes via the GGTT being visible by other physical paths, but we use a
    very heavy workaround for all. We only need to apply that workarounds to
    the chipsets we know suffer from the delay and the resulting coherency
    issue.

    Similarly, the same inconsistent coherency fouls up our ABI promise that
    a write into a mmap_gtt is immediately visible to others. Since the HW
    has made that a lie, let userspace know when that contract is broken.
    (Not that userspace would want to use mmap_gtt on those chipsets for
    other performance reasons...)

    Testcase: igt/drv_selftest/live_coherency
    Testcase: igt/gem_mmap_gtt/coherency
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100587
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
    Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
    Reviewed-by: Tomasz Lis <tomasz.lis at intel.com>
    Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
    Link:
https://patchwork.freedesktop.org/patch/msgid/20180720101910.11153-1-chris@chris-wilson.co.uk

igt commit 65cdccdc7bcbb791d791aeeeecb784a382110a3c (HEAD, upstream/master)
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Fri Jul 20 09:02:26 2018 +0100

    igt/gem_mmap_gtt: Check for known incoherency before testing

    We test map_gtt coherency (whether or not a write via the mmap_gtt is
    immediately visible in the backing storage to a read via mmap_cpu) but
    we know that several platforms are inherently incorrect and require some
    form of hammer to workaround internal delays. These platforms break our
    ABI guarantees and so we report the change in ABI via a driver getparam.

    If we know the platform doesn't meet the ABI guarantee, skip the test.
    If it is meant to work, test!

    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100587
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
    Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
    Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

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