drm: Allow creating blob properties without copy

Make the data parameter to drm_property_create_blob optional; if
omitted, the copy will be skipped and the data will be empty.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@intel.com>
Tested-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index f6b0332aad7f..0844108e19e0 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -4145,6 +4145,16 @@ done:
         return ret;
 }
 
+/**
+ * drm_property_create_blob - Create new blob property
+ *
+ * Creates a new blob property for a specified DRM device, optionally
+ * copying data.
+ *
+ * @dev: DRM device to create property for
+ * @length: Length to allocate for blob data
+ * @data: If specified, copies data into blob
+ */
 struct drm_property_blob *
 drm_property_create_blob(struct drm_device *dev, size_t length,
                          const void *data)
@@ -4152,7 +4162,7 @@ drm_property_create_blob(struct drm_device *dev, size_t length,
         struct drm_property_blob *blob;
         int ret;
 
-        if (!length || !data)
+        if (!length)
                 return NULL;
 
         blob = kzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL);
@@ -4162,7 +4172,8 @@ drm_property_create_blob(struct drm_device *dev, size_t length,
         blob->length = length;
         blob->dev = dev;
 
-        memcpy(blob->data, data, length);
+        if (data)
+                memcpy(blob->data, data, length);
 
         mutex_lock(&dev->mode_config.blob_lock);