drm/i915: restore ggtt double-bind avoidance

This was accidentally lost in

commit 75d04a3
Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Date:   Tue Apr 28 17:56:17 2015 +0300

    drm/i915/gtt: Allocate va range only if vma is not bound

While at it implement an improved version suggested by Chris which
avoids the double-bind irrespective of what type of bind is done
first.

Note that this exact bug was already addressed in

commit d0e30ad
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Wed Jul 29 20:02:48 2015 +0100

    drm/i915: Mark PIN_USER binding as GLOBAL_BIND without the aliasing ppgtt

but the problem is still that originally in

commit 0875546
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Mon Apr 20 09:04:05 2015 -0700

    drm/i915: Fix up the vma aliasing ppgtt binding

if forgotten to take into account there case where we have a
GLOBAL_BIND before a LOCAL_BIND. This patch here fixes that.

v2: Pimp commit message and revert the partial fix.

v3: Split into two functions to specialize on aliasing_ppgtt y/n.

v4: WARN_ON for paranoia in the init sequence, since the ggtt probe
and aliasing ppgtt setup are far apart.

v5: Style nits.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://mid.gmane.org/1444911781-32607-1-git-send-email-daniel.vetter@ffwll.ch
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -2501,6 +2501,36 @@ static void i915_ggtt_clear_range(struct i915_address_space *vm,
 static int ggtt_bind_vma(struct i915_vma *vma,
 			 enum i915_cache_level cache_level,
 			 u32 flags)
+{
+	struct drm_i915_gem_object *obj = vma->obj;
+	u32 pte_flags = 0;
+	int ret;
+
+	ret = i915_get_ggtt_vma_pages(vma);
+	if (ret)
+		return ret;
+
+	/* Currently applicable only to VLV */
+	if (obj->gt_ro)
+		pte_flags |= PTE_READ_ONLY;
+
+	vma->vm->insert_entries(vma->vm, vma->ggtt_view.pages,
+				vma->node.start,
+				cache_level, pte_flags);
+
+	/*
+	 * Without aliasing PPGTT there's no difference between
+	 * GLOBAL/LOCAL_BIND, it's all the same ptes. Hence unconditionally
+	 * upgrade to both bound if we bind either to avoid double-binding.
+	 */
+	vma->bound |= GLOBAL_BIND | LOCAL_BIND;
+
+	return 0;
+}
+
+static int aliasing_gtt_bind_vma(struct i915_vma *vma,
+				 enum i915_cache_level cache_level,
+				 u32 flags)
 {
 	struct drm_device *dev = vma->vm->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -2519,23 +2549,13 @@ static int ggtt_bind_vma(struct i915_vma *vma,
 		pte_flags |= PTE_READ_ONLY;
 
 
-	if (!dev_priv->mm.aliasing_ppgtt || flags & GLOBAL_BIND) {
+	if (flags & GLOBAL_BIND) {
 		vma->vm->insert_entries(vma->vm, pages,
 					vma->node.start,
 					cache_level, pte_flags);
-
-		/* Note the inconsistency here is due to absence of the
-		 * aliasing ppgtt on gen4 and earlier. Though we always
-		 * request PIN_USER for execbuffer (translated to LOCAL_BIND),
-		 * without the appgtt, we cannot honour that request and so
-		 * must substitute it with a global binding. Since we do this
-		 * behind the upper layers back, we need to explicitly set
-		 * the bound flag ourselves.
-		 */
-		vma->bound |= GLOBAL_BIND;
 	}
 
-	if (dev_priv->mm.aliasing_ppgtt && flags & LOCAL_BIND) {
+	if (flags & LOCAL_BIND) {
 		struct i915_hw_ppgtt *appgtt = dev_priv->mm.aliasing_ppgtt;
 		appgtt->base.insert_entries(&appgtt->base, pages,
 					    vma->node.start,
@@ -2699,6 +2719,8 @@ static int i915_gem_setup_global_gtt(struct drm_device *dev,
 					true);
 
 		dev_priv->mm.aliasing_ppgtt = ppgtt;
+		WARN_ON(dev_priv->gtt.base.bind_vma != ggtt_bind_vma);
+		dev_priv->gtt.base.bind_vma = aliasing_gtt_bind_vma;
 	}
 
 	return 0;