drm: GEM CMA: Split object creation into object alloc and DMA memory alloc

This allows creating a GEM CMA object without an associated DMA memory
buffer, and will be used to implement DRM PRIME support.

Change-Id: I9e9e25f7323829939dae993bb7b343e3dfdd8014
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>

diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 0a7e011..8cce330 100644 (file)
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -32,62 +32,73 @@ static unsigned int get_gem_mmap_offset(struct drm_gem_object *obj)
        return (unsigned int)obj->map_list.hash.key << PAGE_SHIFT;
 }
 
-static void drm_gem_cma_buf_destroy(struct drm_device *drm,
-               struct drm_gem_cma_object *cma_obj)
-{
-       dma_free_writecombine(drm->dev, cma_obj->base.size, cma_obj->vaddr,
-                       cma_obj->paddr);
-}
-
 /*
- * drm_gem_cma_create - allocate an object with the given size
+ * __drm_gem_cma_create - Create a GEM CMA object without allocating memory
+ * @drm: The drm device
+ * @size: The GEM object size
  *
- * returns a struct drm_gem_cma_object* on success or ERR_PTR values
- * on failure.
+ * This function creates and initializes a GEM CMA object of the given size, but
+ * doesn't allocate any memory to back the object.
+ *
+ * Return a struct drm_gem_cma_object* on success or ERR_PTR values on failure.
  */
-struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
-               unsigned int size)
+static struct drm_gem_cma_object *
+__drm_gem_cma_create(struct drm_device *drm, unsigned int size)
 {
        struct drm_gem_cma_object *cma_obj;
        struct drm_gem_object *gem_obj;
        int ret;
 
-       size = round_up(size, PAGE_SIZE);
-
        cma_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL);
        if (!cma_obj)
                return ERR_PTR(-ENOMEM);
 
-       cma_obj->vaddr = dma_alloc_writecombine(drm->dev, size,
-                       &cma_obj->paddr, GFP_KERNEL | __GFP_NOWARN);
-       if (!cma_obj->vaddr) {
-               dev_err(drm->dev, "failed to allocate buffer with size %d\n", size);
-               ret = -ENOMEM;
-               goto err_dma_alloc;
-       }
-
        gem_obj = &cma_obj->base;
 
        ret = drm_gem_object_init(drm, gem_obj, size);
        if (ret)
-               goto err_obj_init;
+               goto error;
 
        ret = drm_gem_create_mmap_offset(gem_obj);
-       if (ret)
-               goto err_create_mmap_offset;
+       if (ret) {
+               drm_gem_object_release(gem_obj);
+               goto error;
+       }
 
        return cma_obj;
 
-err_create_mmap_offset:
-       drm_gem_object_release(gem_obj);
+error:
+       kfree(cma_obj);
+       return ERR_PTR(ret);
+}
 
-err_obj_init:
-       drm_gem_cma_buf_destroy(drm, cma_obj);
+/*
+ * drm_gem_cma_create - allocate an object with the given size
+ *
+ * returns a struct drm_gem_cma_object* on success or ERR_PTR values
+ * on failure.
+ */
+struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
+               unsigned int size)
+{
+       struct drm_gem_cma_object *cma_obj;
 
-err_dma_alloc:
-       kfree(cma_obj);
+       size = round_up(size, PAGE_SIZE);
 
-       return ERR_PTR(ret);
+       cma_obj = __drm_gem_cma_create(drm, size);
+       if (IS_ERR(cma_obj))
+               return cma_obj;
+
+       cma_obj->vaddr = dma_alloc_writecombine(drm->dev, size,
+                       &cma_obj->paddr, GFP_KERNEL | __GFP_NOWARN);
+       if (!cma_obj->vaddr) {
+               dev_err(drm->dev, "failed to allocate buffer with size %d\n",
+                       size);
+               drm_gem_cma_free_object(&cma_obj->base);
+               return ERR_PTR(-ENOMEM);
+       }
+
+       return cma_obj;
 }
 EXPORT_SYMBOL_GPL(drm_gem_cma_create);
 
@@ -143,11 +154,13 @@ void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)
        if (gem_obj->map_list.map)
                drm_gem_free_mmap_offset(gem_obj);
 
-       drm_gem_object_release(gem_obj);
-
        cma_obj = to_drm_gem_cma_obj(gem_obj);
 
-       drm_gem_cma_buf_destroy(gem_obj->dev, cma_obj);
+       if (cma_obj->vaddr)
+               dma_free_writecombine(gem_obj->dev->dev, cma_obj->base.size,
+                                     cma_obj->vaddr, cma_obj->paddr);
+
+       drm_gem_object_release(gem_obj);
 
        kfree(cma_obj);
 }