drm/i915: implement SNB workaround for lazy global gtt

PIPE_CONTROL on snb needs global gtt mappings in place to workaround a
hw gotcha. No other commands need such a workaround. Luckily we can
detect a PIPE_CONTROL commands easily because they have a write_domain
= I915_GEM_DOMAIN_INSTRUCTION (and nothing else has that).

v2: Binding the target of such a reloc into the global gtt actually
works instead of binding the source, which is rather pointless ...

v3: Kill a superflous has_global_gtt_mapping assignement noticed by
Chris Wilson.

Reviewed-and-tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 81687af00893ca5c20edfe2256dd5b98da7fdf45..0e051eca36395bbff50c987c491c3aa199fc16a7 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -273,6 +273,7 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
 {
        struct drm_device *dev = obj->base.dev;
        struct drm_gem_object *target_obj;
+       struct drm_i915_gem_object *target_i915_obj;
        uint32_t target_offset;
        int ret = -EINVAL;
 
@@ -281,7 +282,8 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
        if (unlikely(target_obj == NULL))
                return -ENOENT;
 
-       target_offset = to_intel_bo(target_obj)->gtt_offset;
+       target_i915_obj = to_intel_bo(target_obj);
+       target_offset = target_i915_obj->gtt_offset;
 
        /* The target buffer should have appeared before us in the
         * exec_object list, so it should have a GTT space bound by now.
@@ -383,6 +385,16 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
                io_mapping_unmap_atomic(reloc_page);
        }
 
+       /* Sandybridge PPGTT errata: We need a global gtt mapping for MI and
+        * pipe_control writes because the gpu doesn't properly redirect them
+        * through the ppgtt for non_secure batchbuffers. */
+       if (unlikely(IS_GEN6(dev) &&
+           reloc->write_domain == I915_GEM_DOMAIN_INSTRUCTION &&
+           !target_i915_obj->has_global_gtt_mapping)) {
+               i915_gem_gtt_bind_object(target_i915_obj,
+                                        target_i915_obj->cache_level);
+       }
+
        /* and update the user's relocation entry */
        reloc->presumed_offset = target_offset;