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            <b><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [cfl] GPU hang when running UE4Editor"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=110228#c36">Comment # 36</a>
              on <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [cfl] GPU hang when running UE4Editor"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=110228">bug 110228</a>
              from <span class="vcard"><a class="email" href="mailto:jason@jlekstrand.net" title="Jason Ekstrand <jason@jlekstrand.net>"> <span class="fn">Jason Ekstrand</span></a>
</span></b>
        <pre>From Chris Wilson:

diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c
b/drivers/gpu/drm/i915/g
t/intel_workarounds.c
index 704ace01e7f5..890a3bcfacea 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -667,6 +667,10 @@ gen9_gt_workarounds_init(struct drm_i915_private *i915,
stru
ct i915_wa_list *wal
                            MMCD_PCLA | MMCD_HOTSPOT_EN);
        }

+       wa_write_masked_or(wal, _MMIO(0xb008), BIT(0), 0);
+       wa_write_masked_or(wal, _MMIO(0xb118), BIT(22), 0);
+       wa_write_masked_or(wal, _MMIO(0xb11c), BIT(8), 0);
+
        /* WaDisableHDCInvalidation:skl,bxt,kbl,cfl */
        wa_write_or(wal,
                    GAM_ECOCHK,

Assuming none of those registers are protected, we should be able to do that
from userspace and disable the L3$ for just atomics.</pre>
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