drm/i915: Fix gen2 mappable calculations

When I refactored the code initially, I forgot that gen2 uses a
different bar for the CPU mappable aperture. The agp-less code knows
nothing of generations less than 5, so we have to expand the gtt_probe
function to include the mappable base and end.

It was originally broken by me:
commit baa09f5fd8a6d033ec075355dda99a65b7f6a0f3
Author: Ben Widawsky <[e-mail]>
Date: Thu Jan 24 13:49:57 2013 -0800

drm/i915: Add probe and remove to the gtt ops

Reported-by: Chris Wilson <[e-mail]>
Signed-off-by: Ben Widawsky <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>

drivers/char/agp/intel-gtt.c

···
 }
 EXPORT_SYMBOL(intel_gmch_probe);
 
-void intel_gtt_get(size_t *gtt_total, size_t *stolen_size)
+void intel_gtt_get(size_t *gtt_total, size_t *stolen_size,
+		   phys_addr_t *mappable_base, unsigned long *mappable_end)
 {
 	*gtt_total = intel_private.gtt_total_entries << PAGE_SHIFT;
 	*stolen_size = intel_private.stolen_size;
+	*mappable_base = intel_private.gma_bus_addr;
+	*mappable_end = intel_private.gtt_mappable_entries << PAGE_SHIFT;
 }
 EXPORT_SYMBOL(intel_gtt_get);
 

drivers/gpu/drm/i915/i915_drv.h

···
 
 	/* global gtt ops */
 	int (*gtt_probe)(struct drm_device *dev, size_t *gtt_total,
-			  size_t *stolen);
+			  size_t *stolen, phys_addr_t *mappable_base,
+			  unsigned long *mappable_end);
 	void (*gtt_remove)(struct drm_device *dev);
 	void (*gtt_clear_range)(struct drm_device *dev,
 				unsigned int first_entry,

drivers/gpu/drm/i915/i915_gem_gtt.c

···
 
 static int gen6_gmch_probe(struct drm_device *dev,
 			   size_t *gtt_total,
-			   size_t *stolen)
+			   size_t *stolen,
+			   phys_addr_t *mappable_base,
+			   unsigned long *mappable_end)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	phys_addr_t gtt_bus_addr;
···
 	u16 snb_gmch_ctl;
 	int ret;
 
+	*mappable_base = pci_resource_start(dev->pdev, 2);
+	*mappable_end = pci_resource_len(dev->pdev, 2);
+
 	/* 64/512MB is the current min/max we actually know of, but this is just
 	 * a coarse sanity check.
 	 */
-	if ((dev_priv->gtt.mappable_end < (64<<20) ||
-	     (dev_priv->gtt.mappable_end > (512<<20)))) {
+	if ((*mappable_end < (64<<20) || (*mappable_end > (512<<20)))) {
 		DRM_ERROR("Unknown GMADR size (%lx)\n",
 			  dev_priv->gtt.mappable_end);
 		return -ENXIO;
···
 
 static int i915_gmch_probe(struct drm_device *dev,
 			   size_t *gtt_total,
-			   size_t *stolen)
+			   size_t *stolen,
+			   phys_addr_t *mappable_base,
+			   unsigned long *mappable_end)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret;
···
 		return -EIO;
 	}
 
-	intel_gtt_get(gtt_total, stolen);
+	intel_gtt_get(gtt_total, stolen, mappable_base, mappable_end);
 
 	dev_priv->gtt.do_idle_maps = needs_idle_maps(dev_priv->dev);
 	dev_priv->gtt.gtt_clear_range = i915_ggtt_clear_range;
···
 	unsigned long gtt_size;
 	int ret;
 
-	gtt->mappable_base = pci_resource_start(dev->pdev, 2);
-	gtt->mappable_end = pci_resource_len(dev->pdev, 2);
-
 	if (INTEL_INFO(dev)->gen <= 5) {
 		dev_priv->gtt.gtt_probe = i915_gmch_probe;
 		dev_priv->gtt.gtt_remove = i915_gmch_remove;
···
 	}
 
 	ret = dev_priv->gtt.gtt_probe(dev, &dev_priv->gtt.total,
-				     &dev_priv->gtt.stolen_size);
+				     &dev_priv->gtt.stolen_size,
+				     &gtt->mappable_base,
+				     &gtt->mappable_end);
 	if (ret)
 		return ret;
 

include/drm/intel-gtt.h

···
 #ifndef _DRM_INTEL_GTT_H
 #define	_DRM_INTEL_GTT_H
 
-void intel_gtt_get(size_t *gtt_total, size_t *stolen_size);
+void intel_gtt_get(size_t *gtt_total, size_t *stolen_size,
+		   phys_addr_t *mappable_base, unsigned long *mappable_end);
 
 int intel_gmch_probe(struct pci_dev *bridge_pdev, struct pci_dev *gpu_pdev,
 		     struct agp_bridge_data *bridge);