[PATCH 1/3] drm/i915: Stop putting GGTT VMA at the head of the list

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Multiple GGTT VMAs per object will be introduced in the near future which will
make it impossible to guarantee normal GGTT view is at the head of the list.

Purpose of this patch is to break this assumption straight away so any
potential hidden assumptions in the code base can be bisected to this
simple patch.

For: VIZ-4544
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Suggested-by: Daniel Vetter <daniel@ffwll.ch>
---
 drivers/gpu/drm/i915/i915_gem.c     | 10 ++++++----
 drivers/gpu/drm/i915/i915_gem_gtt.c |  8 ++------
 2 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 9d362d3..c1c1141 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5303,11 +5303,13 @@ i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
 
 struct i915_vma *i915_gem_obj_to_ggtt(struct drm_i915_gem_object *obj)
 {
+	struct i915_address_space *ggtt = i915_obj_to_ggtt(obj);
 	struct i915_vma *vma;
 
-	vma = list_first_entry(&obj->vma_list, typeof(*vma), vma_link);
-	if (vma->vm != i915_obj_to_ggtt(obj))
-		return NULL;
+	list_for_each_entry(vma, &obj->vma_list, vma_link) {
+		if (vma->vm == ggtt)
+			return vma;
+	}
 
-	return vma;
+	return NULL;
 }
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 171f6ea..ac03a38 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2202,13 +2202,9 @@ static struct i915_vma *__i915_gem_vma_create(struct drm_i915_gem_object *obj,
 		BUG();
 	}
 
-	/* Keep GGTT vmas first to make debug easier */
-	if (i915_is_ggtt(vm))
-		list_add(&vma->vma_link, &obj->vma_list);
-	else {
-		list_add_tail(&vma->vma_link, &obj->vma_list);
+	list_add_tail(&vma->vma_link, &obj->vma_list);
+	if (!i915_is_ggtt(vm))
 		i915_ppgtt_get(i915_vm_to_ppgtt(vm));
-	}
 
 	return vma;
 }
-- 
2.1.1

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