drm/i915: Add an interface to dynamically change the cache level
[anholt v2: Don't forget that when going from cached to uncached, we
haven't been tracking the write domain from the CPU perspective, since
we haven't needed it for GPU coherency.]
[ickle v3: We also need to make sure we relinquish any fences on older
chipsets and clear the GTT for sane domain tracking.]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e78a7ef..e691507 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3034,6 +3034,66 @@
return 0;
}
+int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
+ enum i915_cache_level cache_level)
+{
+ int ret;
+
+ if (obj->cache_level == cache_level)
+ return 0;
+
+ if (obj->pin_count) {
+ DRM_DEBUG("can not change the cache level of pinned objects\n");
+ return -EBUSY;
+ }
+
+ if (obj->gtt_space) {
+ ret = i915_gem_object_finish_gpu(obj);
+ if (ret)
+ return ret;
+
+ i915_gem_object_finish_gtt(obj);
+
+ /* Before SandyBridge, you could not use tiling or fence
+ * registers with snooped memory, so relinquish any fences
+ * currently pointing to our region in the aperture.
+ */
+ if (INTEL_INFO(obj->base.dev)->gen < 6) {
+ ret = i915_gem_object_put_fence(obj);
+ if (ret)
+ return ret;
+ }
+
+ i915_gem_gtt_rebind_object(obj, cache_level);
+ }
+
+ if (cache_level == I915_CACHE_NONE) {
+ u32 old_read_domains, old_write_domain;
+
+ /* If we're coming from LLC cached, then we haven't
+ * actually been tracking whether the data is in the
+ * CPU cache or not, since we only allow one bit set
+ * in obj->write_domain and have been skipping the clflushes.
+ * Just set it to the CPU cache for now.
+ */
+ WARN_ON(obj->base.write_domain & ~I915_GEM_DOMAIN_CPU);
+ WARN_ON(obj->base.read_domains & ~I915_GEM_DOMAIN_CPU);
+
+ old_read_domains = obj->base.read_domains;
+ old_write_domain = obj->base.write_domain;
+
+ obj->base.read_domains = I915_GEM_DOMAIN_CPU;
+ obj->base.write_domain = I915_GEM_DOMAIN_CPU;
+
+ trace_i915_gem_object_change_domain(obj,
+ old_read_domains,
+ old_write_domain);
+ }
+
+ obj->cache_level = cache_level;
+ return 0;
+}
+
/*
* Prepare buffer for display plane. Use uninterruptible for possible flush
* wait, as in modesetting process we're not supposed to be interrupted.