From 2a11ad520b66f9539dca808ab3f138f46d49e473 Mon Sep 17 00:00:00 2001
From: Johannes Schock <johannes.schock@nivus.com>
Date: Sun, 9 Aug 2020 19:12:17 +0200
Subject: [PATCH] usbhost_storage.c: Fixed Bug in usbhost_freedevno(...),
 worked only for 'a'.

---
 drivers/usbhost/usbhost_storage.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usbhost/usbhost_storage.c b/drivers/usbhost/usbhost_storage.c
index fb398863732..0fe12198b4d 100644
--- a/drivers/usbhost/usbhost_storage.c
+++ b/drivers/usbhost/usbhost_storage.c
@@ -482,7 +482,7 @@ static int usbhost_allocdevno(FAR struct usbhost_state_s *priv)
 
 static void usbhost_freedevno(FAR struct usbhost_state_s *priv)
 {
-  int devno = 'a' - priv->sdchar;
+  int devno = priv->sdchar - 'a';
 
   if (devno >= 0 && devno < 26)
     {