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Commit 149c8407 authored by Daniel Vetter's avatar Daniel Vetter
Browse files

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: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 74898d7e

drivers/gpu/drm/i915/i915_gem_execbuffer.c

+13 −1
Original line number Diff line number Diff line
@@ -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;