drm/i915: Split GGTT initialisation between probing and setup

In order to handle conflicting drivers (i.e. vgacon) having a different
setup of hardware, we have to remove those other drivers before we try
to setup our own mappings. This requires us to split GGTT initialisation
between probing for the hardware location (part of the PCI BAR) and
later establishing the kernel resources for it.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470293567-10811-2-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_drv.c

@@ -1004,16 +1004,10 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
 
 	intel_sanitize_options(dev_priv);
 
-	ret = i915_ggtt_init_hw(dev);
+	ret = i915_ggtt_probe_hw(dev);
 	if (ret)
 		return ret;
 
-	ret = i915_ggtt_enable_hw(dev);
-	if (ret) {
-		DRM_ERROR("failed to enable GGTT\n");
-		goto out_ggtt;
-	}
-
 	/* WARNING: Apparently we must kick fbdev drivers before vgacon,
 	 * otherwise the vga fbdev driver falls over. */
 	ret = i915_kick_out_firmware_fb(dev_priv);
@@ -1028,6 +1022,16 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
 		goto out_ggtt;
 	}
 
+	ret = i915_ggtt_init_hw(dev);
+	if (ret)
+		return ret;
+
+	ret = i915_ggtt_enable_hw(dev);
+	if (ret) {
+		DRM_ERROR("failed to enable GGTT\n");
+		goto out_ggtt;
+	}
+
 	pci_set_master(dev->pdev);
 
 	/* overlay on gen2 is broken and can't address above 1G */

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -3208,10 +3208,10 @@ static void i915_gmch_remove(struct i915_address_space *vm)
 }
 
 /**
- * i915_ggtt_init_hw - Initialize GGTT hardware
+ * i915_ggtt_probe_hw - Probe GGTT hardware location
  * @dev: DRM device
  */
-int i915_ggtt_init_hw(struct drm_device *dev)
+int i915_ggtt_probe_hw(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct i915_ggtt *ggtt = &dev_priv->ggtt;
@@ -3254,14 +3254,6 @@ int i915_ggtt_init_hw(struct drm_device *dev)
 		ggtt->mappable_end = min(ggtt->mappable_end, ggtt->base.total);
 	}
 
-	/*
-	 * Initialise stolen early so that we may reserve preallocated
-	 * objects for the BIOS to KMS transition.
-	 */
-	ret = i915_gem_init_stolen(dev);
-	if (ret)
-		goto out_gtt_cleanup;
-
 	/* GMADR is the PCI mmio aperture into the global GTT. */
 	DRM_INFO("Memory usable by graphics device = %lluM\n",
 		 ggtt->base.total >> 20);
@@ -3273,10 +3265,30 @@ int i915_ggtt_init_hw(struct drm_device *dev)
 #endif
 
 	return 0;
+}
+
+/**
+ * i915_ggtt_init_hw - Initialize GGTT hardware
+ * @dev: DRM device
+ */
+int i915_ggtt_init_hw(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct i915_ggtt *ggtt = &dev_priv->ggtt;
+	int ret;
+
+	/*
+	 * Initialise stolen early so that we may reserve preallocated
+	 * objects for the BIOS to KMS transition.
+	 */
+	ret = i915_gem_init_stolen(dev);
+	if (ret)
+		goto out_gtt_cleanup;
+
+	return 0;
 
 out_gtt_cleanup:
 	ggtt->base.cleanup(&ggtt->base);
-
 	return ret;
 }
 

drivers/gpu/drm/i915/i915_gem_gtt.h

@@ -521,6 +521,7 @@ i915_page_dir_dma_addr(const struct i915_hw_ppgtt *ppgtt, const unsigned n)
 		px_dma(ppgtt->base.scratch_pd);
 }
 
+int i915_ggtt_probe_hw(struct drm_device *dev);
 int i915_ggtt_init_hw(struct drm_device *dev);
 int i915_ggtt_enable_hw(struct drm_device *dev);
 void i915_gem_init_ggtt(struct drm_device *dev);