1 files changed, 49 insertions, 11 deletions

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index 410572f14257..e1dafb0cc5e2 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -254,7 +254,6 @@ drm_client_buffer_create(struct drm_client_dev *client, u32 width, u32 height, u
         struct drm_device *dev = client->dev;
         struct drm_client_buffer *buffer;
         struct drm_gem_object *obj;
-        void *vaddr;
         int ret;
 
         buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
@@ -281,6 +280,36 @@ drm_client_buffer_create(struct drm_client_dev *client, u32 width, u32 height, u
 
         buffer->gem = obj;
 
+        return buffer;
+
+err_delete:
+        drm_client_buffer_delete(buffer);
+
+        return ERR_PTR(ret);
+}
+
+/**
+ * drm_client_buffer_vmap - Map DRM client buffer into address space
+ * @buffer: DRM client buffer
+ *
+ * This function maps a client buffer into kernel address space. If the
+ * buffer is already mapped, it returns the mapping's address.
+ *
+ * Client buffer mappings are not ref'counted. Each call to
+ * drm_client_buffer_vmap() should be followed by a call to
+ * drm_client_buffer_vunmap(); or the client buffer should be mapped
+ * throughout its lifetime.
+ *
+ * Returns:
+ *      The mapped memory's address
+ */
+void *drm_client_buffer_vmap(struct drm_client_buffer *buffer)
+{
+        void *vaddr;
+
+        if (buffer->vaddr)
+                return buffer->vaddr;
+
         /*
          * FIXME: The dependency on GEM here isn't required, we could
          * convert the driver handle to a dma-buf instead and use the
@@ -289,21 +318,30 @@ drm_client_buffer_create(struct drm_client_dev *client, u32 width, u32 height, u
          * fd_install step out of the driver backend hooks, to make that
          * final step optional for internal users.
          */
-        vaddr = drm_gem_vmap(obj);
-        if (IS_ERR(vaddr)) {
-                ret = PTR_ERR(vaddr);
-                goto err_delete;
-        }
+        vaddr = drm_gem_vmap(buffer->gem);
+        if (IS_ERR(vaddr))
+                return vaddr;
 
         buffer->vaddr = vaddr;
 
-        return buffer;
-
-err_delete:
-        drm_client_buffer_delete(buffer);
+        return vaddr;
+}
+EXPORT_SYMBOL(drm_client_buffer_vmap);
 
-        return ERR_PTR(ret);
+/**
+ * drm_client_buffer_vunmap - Unmap DRM client buffer
+ * @buffer: DRM client buffer
+ *
+ * This function removes a client buffer's memory mapping. Calling this
+ * function is only required by clients that manage their buffer mappings
+ * by themselves.
+ */
+void drm_client_buffer_vunmap(struct drm_client_buffer *buffer)
+{
+        drm_gem_vunmap(buffer->gem, buffer->vaddr);
+        buffer->vaddr = NULL;
 }
+EXPORT_SYMBOL(drm_client_buffer_vunmap);
 
 static void drm_client_buffer_rmfb(struct drm_client_buffer *buffer)
 {