mtd: part: Create the master device node when partitioned

[firefly-linux-kernel-4.4.55.git] / drivers / mtd / mtdpart.c

diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index e779de315ade505f1a508edefc541f7a4223af97..a19ec5a4e4095888ad8aaba63496d84328f18040 100644 (file)
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -30,6 +30,7 @@
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/partitions.h>
 #include <linux/err.h>
+#include <linux/kconfig.h>
 
 #include "mtdcore.h"
 
@@ -379,10 +380,17 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
        slave->mtd.name = name;
        slave->mtd.owner = master->owner;
 
-       /* NOTE:  we don't arrange MTDs as a tree; it'd be error-prone
-        * to have the same data be in two different partitions.
+       /* NOTE: Historically, we didn't arrange MTDs as a tree out of
+        * concern for showing the same data in multiple partitions.
+        * However, it is very useful to have the master node present,
+        * so the MTD_PARTITIONED_MASTER option allows that. The master
+        * will have device nodes etc only if this is set, so make the
+        * parent conditional on that option. Note, this is a way to
+        * distinguish between the master and the partition in sysfs.
         */
-       slave->mtd.dev.parent = master->dev.parent;
+       slave->mtd.dev.parent = IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) ?
+                               &master->dev :
+                               master->dev.parent;
 
        slave->mtd._read = part_read;
        slave->mtd._write = part_write;
@@ -631,8 +639,8 @@ EXPORT_SYMBOL_GPL(mtd_del_partition);
  * and registers slave MTD objects which are bound to the master according to
  * the partition definitions.
  *
- * We don't register the master, or expect the caller to have done so,
- * for reasons of data integrity.
+ * For historical reasons, this function's caller only registers the master
+ * if the MTD_PARTITIONED_MASTER config option is set.
  */
 
 int add_mtd_partitions(struct mtd_info *master,