drm/i915/stolen: make the object creation interface consistent

Our other backends return an actual error value upon failure. Do the
same for stolen objects, which currently just return NULL on failure.
Signed-off-by: CQ Tang <cq.tang@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191004170452.15410-2-matthew.auld@intel.com

drivers/gpu/drm/i915/display/intel_display.c

@@ -3066,7 +3066,7 @@ intel_alloc_initial_plane_obj(struct intel_crtc *crtc,
 							     base_aligned,
 							     base_aligned,
 							     size_aligned);
-	if (!obj)
+	if (IS_ERR(obj))
 		return false;
 
 	switch (plane_config->tiling) {

drivers/gpu/drm/i915/display/intel_fbdev.c

@@ -141,10 +141,10 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
 	/* If the FB is too big, just don't use it since fbdev is not very
 	 * important and we should probably use that space with FBC or other
 	 * features. */
-	obj = NULL;
+	obj = ERR_PTR(-ENODEV);
 	if (size * 2 < dev_priv->stolen_usable_size)
 		obj = i915_gem_object_create_stolen(dev_priv, size);
-	if (obj == NULL)
+	if (IS_ERR(obj))
 		obj = i915_gem_object_create_shmem(dev_priv, size);
 	if (IS_ERR(obj)) {
 		DRM_ERROR("failed to allocate framebuffer\n");

drivers/gpu/drm/i915/display/intel_overlay.c

@@ -1291,7 +1291,7 @@ static int get_registers(struct intel_overlay *overlay, bool use_phys)
 	int err;
 
 	obj = i915_gem_object_create_stolen(i915, PAGE_SIZE);
-	if (obj == NULL)
+	if (IS_ERR(obj))
 		obj = i915_gem_object_create_internal(i915, PAGE_SIZE);
 	if (IS_ERR(obj))
 		return PTR_ERR(obj);

drivers/gpu/drm/i915/gem/i915_gem_stolen.c

@@ -553,10 +553,11 @@ _i915_gem_object_create_stolen(struct drm_i915_private *dev_priv,
 {
 	struct drm_i915_gem_object *obj;
 	unsigned int cache_level;
+	int err = -ENOMEM;
 
 	obj = i915_gem_object_alloc();
-	if (obj == NULL)
-		return NULL;
+	if (!obj)
+		goto err;
 
 	drm_gem_private_object_init(&dev_priv->drm, &obj->base, stolen->size);
 	i915_gem_object_init(obj, &i915_gem_object_stolen_ops);
@@ -566,14 +567,16 @@ _i915_gem_object_create_stolen(struct drm_i915_private *dev_priv,
 	cache_level = HAS_LLC(dev_priv) ? I915_CACHE_LLC : I915_CACHE_NONE;
 	i915_gem_object_set_cache_coherency(obj, cache_level);
 
-	if (i915_gem_object_pin_pages(obj))
+	err = i915_gem_object_pin_pages(obj);
+	if (err)
 		goto cleanup;
 
 	return obj;
 
 cleanup:
 	i915_gem_object_free(obj);
-	return NULL;
+err:
+	return ERR_PTR(err);
 }
 
 struct drm_i915_gem_object *
@@ -585,28 +588,32 @@ i915_gem_object_create_stolen(struct drm_i915_private *dev_priv,
 	int ret;
 
 	if (!drm_mm_initialized(&dev_priv->mm.stolen))
-		return NULL;
+		return ERR_PTR(-ENODEV);
 
 	if (size == 0)
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	stolen = kzalloc(sizeof(*stolen), GFP_KERNEL);
 	if (!stolen)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	ret = i915_gem_stolen_insert_node(dev_priv, stolen, size, 4096);
 	if (ret) {
-		kfree(stolen);
-		return NULL;
+		obj = ERR_PTR(ret);
+		goto err_free;
 	}
 
 	obj = _i915_gem_object_create_stolen(dev_priv, stolen);
-	if (obj)
-		return obj;
+	if (IS_ERR(obj))
+		goto err_remove;
 
+	return obj;
+
+err_remove:
 	i915_gem_stolen_remove_node(dev_priv, stolen);
+err_free:
 	kfree(stolen);
-	return NULL;
+	return obj;
 }
 
 struct drm_i915_gem_object *
@@ -622,7 +629,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_i915_private *dev_priv
 	int ret;
 
 	if (!drm_mm_initialized(&dev_priv->mm.stolen))
-		return NULL;
+		return ERR_PTR(-ENODEV);
 
 	DRM_DEBUG_DRIVER("creating preallocated stolen object: stolen_offset=%pa, gtt_offset=%pa, size=%pa\n",
 			 &stolen_offset, &gtt_offset, &size);
@@ -631,11 +638,11 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_i915_private *dev_priv
 	if (WARN_ON(size == 0) ||
 	    WARN_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE)) ||
 	    WARN_ON(!IS_ALIGNED(stolen_offset, I915_GTT_MIN_ALIGNMENT)))
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	stolen = kzalloc(sizeof(*stolen), GFP_KERNEL);
 	if (!stolen)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	stolen->start = stolen_offset;
 	stolen->size = size;
@@ -645,15 +652,15 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_i915_private *dev_priv
 	if (ret) {
 		DRM_DEBUG_DRIVER("failed to allocate stolen space\n");
 		kfree(stolen);
-		return NULL;
+		return ERR_PTR(ret);
 	}
 
 	obj = _i915_gem_object_create_stolen(dev_priv, stolen);
-	if (obj == NULL) {
+	if (IS_ERR(obj)) {
 		DRM_DEBUG_DRIVER("failed to allocate stolen object\n");
 		i915_gem_stolen_remove_node(dev_priv, stolen);
 		kfree(stolen);
-		return NULL;
+		return obj;
 	}
 
 	/* Some objects just need physical mem from stolen space */
@@ -706,5 +713,5 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_i915_private *dev_priv
 	i915_gem_object_unpin_pages(obj);
 err:
 	i915_gem_object_put(obj);
-	return NULL;
+	return ERR_PTR(ret);
 }

drivers/gpu/drm/i915/gt/intel_gt.c

@@ -334,7 +334,7 @@ static int intel_gt_init_scratch(struct intel_gt *gt, unsigned int size)
 	int ret;
 
 	obj = i915_gem_object_create_stolen(i915, size);
-	if (!obj)
+	if (IS_ERR(obj))
 		obj = i915_gem_object_create_internal(i915, size);
 	if (IS_ERR(obj)) {
 		DRM_ERROR("Failed to allocate scratch page\n");

drivers/gpu/drm/i915/gt/intel_rc6.c

@@ -299,8 +299,8 @@ static int vlv_rc6_init(struct intel_rc6 *rc6)
 								      pcbr_offset,
 								      I915_GTT_OFFSET_NONE,
 								      pctx_size);
-		if (!pctx)
-			return -ENOMEM;
+		if (IS_ERR(pctx))
+			return PTR_ERR(pctx);
 
 		goto out;
 	}
@@ -316,9 +316,9 @@ static int vlv_rc6_init(struct intel_rc6 *rc6)
 	 * memory, or any other relevant ranges.
 	 */
 	pctx = i915_gem_object_create_stolen(i915, pctx_size);
-	if (!pctx) {
+	if (IS_ERR(pctx)) {
 		DRM_DEBUG("not enough stolen space for PCTX, disabling\n");
-		return -ENOMEM;
+		return PTR_ERR(pctx);
 	}
 
 	GEM_BUG_ON(range_overflows_t(u64,

drivers/gpu/drm/i915/gt/intel_ringbuffer.c

@@ -1274,7 +1274,7 @@ static struct i915_vma *create_ring_vma(struct i915_ggtt *ggtt, int size)
 	struct i915_vma *vma;
 
 	obj = i915_gem_object_create_stolen(i915, size);
-	if (!obj)
+	if (IS_ERR(obj))
 		obj = i915_gem_object_create_internal(i915, size);
 	if (IS_ERR(obj))
 		return ERR_CAST(obj);