dma-debug: add comment for failed to check map error
Add comment for failure to check a map error to help driver developers.
Link: http://lkml.kernel.org/r/1484622289-22085-1-git-send-email-miles.chen@mediatek.com
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 8971370..60c57ec 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -1155,6 +1155,11 @@ static void check_unmap(struct dma_debug_entry *ref)
dir2name[ref->direction]);
}
+ /*
+ * Drivers should use dma_mapping_error() to check the returned
+ * addresses of dma_map_single() and dma_map_page().
+ * If not, print this warning message. See Documentation/DMA-API.txt.
+ */
if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
err_printk(ref->dev, entry,
"DMA-API: device driver failed to check map error"