dm: blk: Add a comment as to why the bdev member is needed

This member should be explained, since it is not obvious why it is needed.
Add a comment.

Signed-off-by: Simon Glass <sjg@chromium.org>

diff --git a/include/blk.h b/include/blk.h
index 3fa373e208b932577e7eb6ca6b6851aff9998f9b..66a1c55cc8b69c256e9caf214642bbc60c439406 100644 (file)
--- a/include/blk.h
+++ b/include/blk.h
@@ -63,6 +63,11 @@ struct blk_desc {
        char            product[20+1];  /* IDE Serial no, SCSI product */
        char            revision[8+1];  /* firmware revision */
 #ifdef CONFIG_BLK
+       /*
+        * For now we have a few functions which take struct blk_desc as a
+        * parameter. This field allows them to look up the associated
+        * device. Once these functions are removed we can drop this field.
+        */
        struct udevice *bdev;
 #else
        unsigned long   (*block_read)(struct blk_desc *block_dev,