drm/v3d: Invalidate the caches from the outside in.

This would be a fairly obscure race, but let's make sure we don't ever
lose it.

Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20181203222438.25417-6-eric@anholt.net
Reviewed-by: Dave Emett <david.emett@broadcom.com>

diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
index 06525ea..803f314 100644 (file)
--- a/drivers/gpu/drm/v3d/v3d_gem.c
+++ b/drivers/gpu/drm/v3d/v3d_gem.c
@@ -171,11 +171,15 @@ v3d_invalidate_slices(struct v3d_dev *v3d, int core)
 void
 v3d_invalidate_caches(struct v3d_dev *v3d)
 {
+       /* Invalidate the caches from the outside in.  That way if
+        * another CL's concurrent use of nearby memory were to pull
+        * an invalidated cacheline back in, we wouldn't leave stale
+        * data in the inner cache.
+        */
        v3d_flush_l3(v3d);
-
        v3d_invalidate_l2c(v3d, 0);
-       v3d_invalidate_slices(v3d, 0);
        v3d_flush_l2t(v3d, 0);
+       v3d_invalidate_slices(v3d, 0);
 }
 
 static void