diff --git a/drivers/firmware/meson/meson_sm.c b/drivers/firmware/meson/meson_sm.c
index 5f30a5774e57..ff204421117b 100644
--- a/drivers/firmware/meson/meson_sm.c
+++ b/drivers/firmware/meson/meson_sm.c
@@ -136,11 +136,14 @@ EXPORT_SYMBOL(meson_sm_call);
  * @arg4:	SMC32 Argument 4
  *
  * Return:	size of read data on success, a negative value on error
+ *		When 0 is returned there is no guarantee about the amount of
+ *		data read and bsize bytes are copied in buffer.
  */
 int meson_sm_call_read(void *buffer, unsigned int bsize, unsigned int cmd_index,
 		       u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4)
 {
 	u32 size;
+	int ret;
 
 	if (!fw.chip)
 		return -ENOENT;
@@ -154,13 +157,18 @@ int meson_sm_call_read(void *buffer, unsigned int bsize, unsigned int cmd_index,
 	if (meson_sm_call(cmd_index, &size, arg0, arg1, arg2, arg3, arg4) < 0)
 		return -EINVAL;
 
-	if (!size || size > bsize)
+	if (size > bsize)
 		return -EINVAL;
 
+	ret = size;
+
+	if (!size)
+		size = bsize;
+
 	if (buffer)
 		memcpy(buffer, fw.sm_shmem_out_base, size);
 
-	return size;
+	return ret;
 }
 EXPORT_SYMBOL(meson_sm_call_read);