[MTD] Clarify OOB-operation interface comments

Add more comment to OOB I/O interface. Read/write are not
symmetric which is confusing and should be documented.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 8a2e8bf..6a8570b 100644 (file)
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -85,6 +85,10 @@ typedef enum {
  *             mode = MTD_OOB_PLACE)
  * @datbuf:    data buffer - if NULL only oob data are read/written
  * @oobbuf:    oob data buffer
+ *
+ * Note, it is allowed to read more then one OOB area at one go, but not write.
+ * The interface assumes that the OOB write requests program only one page's
+ * OOB area.
  */
 struct mtd_oob_ops {
        mtd_oob_mode_t  mode;