diff options
| author | Chris Wilson <chris@chris-wilson.co.uk> | 2018-07-06 18:49:26 +0100 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2018-07-06 21:28:11 +0100 |
| commit | 3a32497f0dbe170794e1506deb41dc44c4fea8d9 (patch) | |
| tree | f62703594d024a6d75e61178c4023ad098c05787 | |
| parent | 8b293eb53a7d7605f762351918083a4e402dc784 (diff) | |
drm/i915/selftests: Provide full mb() around clflush
clflush is an unserialised instruction and the IA manual strongly advises
you to serialise it with a mb. To be cautious, apply one before and one
after, so that it is serialised with both writes and reads without
worrying too much about the required direction.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180706174926.4712-1-chris@chris-wilson.co.uk
| -rw-r--r-- | drivers/gpu/drm/i915/selftests/i915_gem_coherency.c | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c b/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c index 1de7c1402fd5..3a095c37c120 100644 --- a/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c +++ b/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c @@ -42,11 +42,21 @@ static int cpu_set(struct drm_i915_gem_object *obj, page = i915_gem_object_get_page(obj, offset >> PAGE_SHIFT); map = kmap_atomic(page); - if (needs_clflush & CLFLUSH_BEFORE) + + if (needs_clflush & CLFLUSH_BEFORE) { + mb(); clflush(map+offset_in_page(offset) / sizeof(*map)); + mb(); + } + map[offset_in_page(offset) / sizeof(*map)] = v; - if (needs_clflush & CLFLUSH_AFTER) + + if (needs_clflush & CLFLUSH_AFTER) { + mb(); clflush(map+offset_in_page(offset) / sizeof(*map)); + mb(); + } + kunmap_atomic(map); i915_gem_obj_finish_shmem_access(obj); @@ -68,8 +78,13 @@ static int cpu_get(struct drm_i915_gem_object *obj, page = i915_gem_object_get_page(obj, offset >> PAGE_SHIFT); map = kmap_atomic(page); - if (needs_clflush & CLFLUSH_BEFORE) + + if (needs_clflush & CLFLUSH_BEFORE) { + mb(); clflush(map+offset_in_page(offset) / sizeof(*map)); + mb(); + } + *v = map[offset_in_page(offset) / sizeof(*map)]; kunmap_atomic(map); |