drm/i915: Move compressed_fb to static allocation

We are already using the size to determine whether or not to free the
object, so there is no functional change there. Almost everything else
has changed to static allocations of the drm_mm_node too.

Aside from bringing this inline with much of our other code, this makes
error paths slightly simpler, which benefits the look of an upcoming
patch.
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_drv.h

@@ -604,7 +604,7 @@ struct i915_fbc {
 	enum plane plane;
 	int y;
 
-	struct drm_mm_node *compressed_fb;
+	struct drm_mm_node compressed_fb;
 	struct drm_mm_node *compressed_llb;
 
 	struct intel_fbc_work {

drivers/gpu/drm/i915/i915_gem_stolen.c

@@ -106,27 +106,25 @@ static unsigned long i915_stolen_to_physical(struct drm_device *dev)
 static int i915_setup_compression(struct drm_device *dev, int size)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct drm_mm_node *compressed_fb, *uninitialized_var(compressed_llb);
+	struct drm_mm_node *uninitialized_var(compressed_llb);
 	int ret;
 
-	compressed_fb = kzalloc(sizeof(*compressed_fb), GFP_KERNEL);
-	if (!compressed_fb)
-		goto err_llb;
-
 	/* Try to over-allocate to reduce reallocations and fragmentation */
-	ret = drm_mm_insert_node(&dev_priv->mm.stolen, compressed_fb,
+	ret = drm_mm_insert_node(&dev_priv->mm.stolen,
+				 &dev_priv->fbc.compressed_fb,
 				 size <<= 1, 4096, DRM_MM_SEARCH_DEFAULT);
 	if (ret)
-		ret = drm_mm_insert_node(&dev_priv->mm.stolen, compressed_fb,
+		ret = drm_mm_insert_node(&dev_priv->mm.stolen,
+					 &dev_priv->fbc.compressed_fb,
 					 size >>= 1, 4096,
 					 DRM_MM_SEARCH_DEFAULT);
 	if (ret)
 		goto err_llb;
 
 	if (HAS_PCH_SPLIT(dev))
-		I915_WRITE(ILK_DPFC_CB_BASE, compressed_fb->start);
+		I915_WRITE(ILK_DPFC_CB_BASE, dev_priv->fbc.compressed_fb.start);
 	else if (IS_GM45(dev)) {
-		I915_WRITE(DPFC_CB_BASE, compressed_fb->start);
+		I915_WRITE(DPFC_CB_BASE, dev_priv->fbc.compressed_fb.start);
 	} else {
 		compressed_llb = kzalloc(sizeof(*compressed_llb), GFP_KERNEL);
 		if (!compressed_llb)
@@ -140,12 +138,11 @@ static int i915_setup_compression(struct drm_device *dev, int size)
 		dev_priv->fbc.compressed_llb = compressed_llb;
 
 		I915_WRITE(FBC_CFB_BASE,
-			   dev_priv->mm.stolen_base + compressed_fb->start);
+			   dev_priv->mm.stolen_base + dev_priv->fbc.compressed_fb.start);
 		I915_WRITE(FBC_LL_BASE,
 			   dev_priv->mm.stolen_base + compressed_llb->start);
 	}
 
-	dev_priv->fbc.compressed_fb = compressed_fb;
 	dev_priv->fbc.size = size;
 
 	DRM_DEBUG_KMS("reserved %d bytes of contiguous stolen space for FBC\n",
@@ -155,9 +152,8 @@ static int i915_setup_compression(struct drm_device *dev, int size)
 
 err_fb:
 	kfree(compressed_llb);
-	drm_mm_remove_node(compressed_fb);
+	drm_mm_remove_node(&dev_priv->fbc.compressed_fb);
 err_llb:
-	kfree(compressed_fb);
 	pr_info_once("drm: not enough stolen space for compressed buffer (need %d more bytes), disabling. Hint: you may be able to increase stolen memory size in the BIOS to avoid this.\n", size);
 	return -ENOSPC;
 }
@@ -185,10 +181,7 @@ void i915_gem_stolen_cleanup_compression(struct drm_device *dev)
 	if (dev_priv->fbc.size == 0)
 		return;
 
-	if (dev_priv->fbc.compressed_fb) {
-		drm_mm_remove_node(dev_priv->fbc.compressed_fb);
-		kfree(dev_priv->fbc.compressed_fb);
-	}
+	drm_mm_remove_node(&dev_priv->fbc.compressed_fb);
 
 	if (dev_priv->fbc.compressed_llb) {
 		drm_mm_remove_node(dev_priv->fbc.compressed_llb);