fdt: Improve the comment for fdt_shrink_to_minimum()

Add a bit more detail about what this function does.

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

diff --git a/boot/fdt_support.c b/boot/fdt_support.c
index b15d07765fec0a7299dc0efc7a325eed0855081e..090d82ee80a50f7e654055d65b4c9dae165e4b63 100644 (file)
--- a/boot/fdt_support.c
+++ b/boot/fdt_support.c
@@ -667,7 +667,6 @@ int fdt_record_loadable(void *blob, u32 index, const char *name,
        return node;
 }
 
-/* Resize the fdt to its actual size + a bit of padding */
 int fdt_shrink_to_minimum(void *blob, uint extrasize)
 {
        int i;

diff --git a/include/fdt_support.h b/include/fdt_support.h
index feda0d997409634ac9d16c5ff5f81367477a29e8..0601f5f7dc8ba269d55ee8a0de8b986f235c9438 100644 (file)
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -232,13 +232,23 @@ int ft_system_setup(void *blob, struct bd_info *bd);
 void set_working_fdt_addr(ulong addr);
 
 /**
- * shrink down the given blob to minimum size + some extrasize if required
+ * fdt_shrink_to_minimum() - shrink FDT while allowing for some margin
+ *
+ * Shrink down the given blob to 'minimum' size + some extrasize.
+ *
+ * The new size is enough to hold the existing contents plus @extrasize bytes,
+ * plus 5 memory reservations. Also, the end of the FDT is aligned to a 4KB
+ * boundary, so it might end up up to 4KB larger than needed.
+ *
+ * If there is an existing memory reservation for @blob in the FDT, it is
+ * updated for the new size.
  *
  * @param blob         FDT blob to update
  * @param extrasize    additional bytes needed
  * Return: 0 if ok, or -FDT_ERR_... on error
  */
 int fdt_shrink_to_minimum(void *blob, uint extrasize);
+
 int fdt_increase_size(void *fdt, int add_len);
 
 int fdt_delete_disabled_nodes(void *blob);