drm/i915: kick any firmware framebuffers before claiming the gtt

Especially vesafb likes to map everything as uc- (yikes), and if that
mapping hangs around still while we try to map the gtt as wc the
kernel will downgrade our request to uc-, resulting in abyssal
performance.

Unfortunately we can't do this as early as readon does (i.e. as the
first thing we do when initializing the hw) because our fb/mmio space
region moves around on a per-gen basis. So I've had to move it below
the gtt initialization, but that seems to work, too. The important
thing is that we do this before we set up the gtt wc mapping.

Now an altogether different question is why people compile their
kernels with vesafb enabled, but I guess making things just work isn't
bad per se ...

v2:
- s/radeondrmfb/inteldrmfb/
- fix up error handling

v3: Kill #ifdef X86, this is Intel after all. Noticed by Ben Widawsky.

v4: Jani Nikula complained about the pointless bool primary
initialization.

v5: Don't oops if we can't allocate, noticed by Chris Wilson.

v6: Resolve conflicts with agp rework and fixup whitespace.

Reported-and-tested-by: "Kilarski, Bernard R" <bernard.r.kilarski@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_dma.c

@@ -1404,6 +1404,27 @@ i915_mtrr_setup(struct drm_i915_private *dev_priv, unsigned long base,
 	}
 }
 
+static void i915_kick_out_firmware_fb(struct drm_i915_private *dev_priv)
+{
+	struct apertures_struct *ap;
+	struct pci_dev *pdev = dev_priv->dev->pdev;
+	bool primary;
+
+	ap = alloc_apertures(1);
+	if (!ap)
+		return;
+
+	ap->ranges[0].base = dev_priv->dev->agp->base;
+	ap->ranges[0].size =
+		dev_priv->mm.gtt->gtt_mappable_entries << PAGE_SHIFT;
+	primary =
+		pdev->resource[PCI_ROM_RESOURCE].flags & IORESOURCE_ROM_SHADOW;
+
+	remove_conflicting_framebuffers(ap, "inteldrmfb", primary);
+
+	kfree(ap);
+}
+
 /**
  * i915_driver_load - setup chip and create an initial config
  * @dev: DRM device
@@ -1449,6 +1470,22 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 		goto free_priv;
 	}
 
+	ret = intel_gmch_probe(dev_priv->bridge_dev, dev->pdev, NULL);
+	if (!ret) {
+		DRM_ERROR("failed to set up gmch\n");
+		ret = -EIO;
+		goto put_bridge;
+	}
+
+	dev_priv->mm.gtt = intel_gtt_get();
+	if (!dev_priv->mm.gtt) {
+		DRM_ERROR("Failed to initialize GTT\n");
+		ret = -ENODEV;
+		goto put_gmch;
+	}
+
+	i915_kick_out_firmware_fb(dev_priv);
+
 	pci_set_master(dev->pdev);
 
 	/* overlay on gen2 is broken and can't address above 1G */
@@ -1471,20 +1508,6 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	if (!dev_priv->regs) {
 		DRM_ERROR("failed to map registers\n");
 		ret = -EIO;
-		goto put_bridge;
-	}
-
-	ret = intel_gmch_probe(dev_priv->bridge_dev, dev->pdev, NULL);
-	if (!ret) {
-		DRM_ERROR("failed to set up gmch\n");
-		ret = -EIO;
-		goto out_rmmap;
-	}
-
-	dev_priv->mm.gtt = intel_gtt_get();
-	if (!dev_priv->mm.gtt) {
-		DRM_ERROR("Failed to initialize GTT\n");
-		ret = -ENODEV;
 		goto put_gmch;
 	}
 
@@ -1496,7 +1519,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 				     aperture_size);
 	if (dev_priv->mm.gtt_mapping == NULL) {
 		ret = -EIO;
-		goto put_gmch;
+		goto out_rmmap;
 	}
 
 	i915_mtrr_setup(dev_priv, dev_priv->mm.gtt_base_addr,
@@ -1618,10 +1641,10 @@ out_mtrrfree:
 		dev_priv->mm.gtt_mtrr = -1;
 	}
 	io_mapping_free(dev_priv->mm.gtt_mapping);
-put_gmch:
-	intel_gmch_remove();
 out_rmmap:
 	pci_iounmap(dev->pdev, dev_priv->regs);
+put_gmch:
+	intel_gmch_remove();
 put_bridge:
 	pci_dev_put(dev_priv->bridge_dev);
 free_priv: