[Mesa-dev] [PATCH] i965: Mark all EGLimages as non-coherent.

Kenneth Graunke kenneth at whitecape.org
Wed Aug 16 19:30:21 UTC 2017

EGLimages are shared with external users, and we don't know what they're
going to do with them.  They might scan them out.  They might access
them in a way that doesn't work with our explicit clflushing.

It's safest to simply mark them non-coherent.

Chris Wilson caught this problem and wrote a similar (though less
aggressive) patch to solve it; the miptree code has since undergone
a lot of refactoring so I had to rewrite it.

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Jason Ekstrand <jason at jlekstrand.net>
 src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
index 237ab182712..dab60c4b045 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
@@ -1061,12 +1061,10 @@ intel_miptree_create_for_dri_image(struct brw_context *brw,
-   /* If this is a window-system image, then we can no longer assume it's
-    * cache-coherent because it may suddenly get scanned out which destroys
-    * coherency.
+   /* Don't assume coherency for imported EGLimages.  We don't know what
+    * external clients are going to do with it.  They may scan it out.
-   if (is_winsys_image)
-      image->bo->cache_coherent = false;
+   image->bo->cache_coherent = false;
    return mt;

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