drm/i915: Reorganize intel_enable_ppgtt

This patch consolidates the way in which we handle the various supported
PPGTT by module parameter in addition to what the hardware supports. It
strives to make doing the right thing in the code as simple as possible,
with the USES_ macros.

I've opted to add the full PPGTT argument simply so one can see how I
intend to use this function. It will not/cannot be used until later.
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -1828,7 +1828,8 @@ struct drm_i915_file_private {
 #define I915_NEED_GFX_HWS(dev)	(INTEL_INFO(dev)->need_gfx_hws)
 
 #define HAS_HW_CONTEXTS(dev)	(INTEL_INFO(dev)->gen >= 6)
-#define HAS_ALIASING_PPGTT(dev)	(INTEL_INFO(dev)->gen >=6 && !IS_VALLEYVIEW(dev))
+#define HAS_ALIASING_PPGTT(dev)	(INTEL_INFO(dev)->gen >= 6 && !IS_VALLEYVIEW(dev))
+#define USES_ALIASING_PPGTT(dev) intel_enable_ppgtt(dev, false)
 
 #define HAS_OVERLAY(dev)		(INTEL_INFO(dev)->has_overlay)
 #define OVERLAY_NEEDS_PHYSICAL(dev)	(INTEL_INFO(dev)->overlay_needs_physical)
@@ -2272,6 +2273,25 @@ static inline void i915_gem_chipset_flush(struct drm_device *dev)
 	if (INTEL_INFO(dev)->gen < 6)
 		intel_gtt_chipset_flush();
 }
+int i915_gem_init_ppgtt(struct drm_device *dev, struct i915_hw_ppgtt *ppgtt);
+static inline bool intel_enable_ppgtt(struct drm_device *dev, bool full)
+{
+	if (i915_enable_ppgtt == 0 || !HAS_ALIASING_PPGTT(dev))
+		return false;
+
+	BUG_ON(full);
+
+#ifdef CONFIG_INTEL_IOMMU
+	/* Disable ppgtt on SNB if VT-d is on. */
+	if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped) {
+		DRM_INFO("Disabling PPGTT because VT-d is on\n");
+		return false;
+	}
+#endif
+
+	return HAS_ALIASING_PPGTT(dev);
+}
+
 
 
 /* i915_gem_evict.c */

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -888,8 +888,7 @@ static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 	return ret;
 }
 
-static int i915_gem_init_ppgtt(struct drm_device *dev,
-			       struct i915_hw_ppgtt *ppgtt)
+int i915_gem_init_ppgtt(struct drm_device *dev, struct i915_hw_ppgtt *ppgtt)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret = 0;
@@ -1397,21 +1396,6 @@ void i915_gem_setup_global_gtt(struct drm_device *dev,
 	ggtt_vm->clear_range(ggtt_vm, end / PAGE_SIZE - 1, 1, true);
 }
 
-static bool
-intel_enable_ppgtt(struct drm_device *dev)
-{
-	if (i915_enable_ppgtt >= 0)
-		return i915_enable_ppgtt;
-
-#ifdef CONFIG_INTEL_IOMMU
-	/* Disable ppgtt on SNB if VT-d is on. */
-	if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped)
-		return false;
-#endif
-
-	return true;
-}
-
 void i915_gem_init_global_gtt(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -1421,7 +1405,7 @@ void i915_gem_init_global_gtt(struct drm_device *dev)
 	mappable_size = dev_priv->gtt.mappable_end;
 
 	i915_gem_setup_global_gtt(dev, 0, mappable_size, gtt_size);
-	if (intel_enable_ppgtt(dev) && HAS_ALIASING_PPGTT(dev)) {
+	if (USES_ALIASING_PPGTT(dev)) {
 		struct i915_hw_ppgtt *ppgtt;
 		int ret;