diff --git a/src/class/msc/msc_device.h b/src/class/msc/msc_device.h
index 74be7e06d..1d223991b 100644
--- a/src/class/msc/msc_device.h
+++ b/src/class/msc/msc_device.h
@@ -31,6 +31,9 @@
 #include "device/usbd.h"
 #include "msc.h"
 
+#ifdef __cplusplus
+ extern "C" {
+#endif
 
 //--------------------------------------------------------------------+
 // Class Driver Configuration
@@ -59,10 +62,6 @@ TU_VERIFY_STATIC(CFG_TUD_MSC_BUFSIZE < UINT16_MAX, "Size is not correct");
   #error CFG_TUD_MSC_PRODUCT_REV 4-byte string must be defined
 #endif
 
-#ifdef __cplusplus
- extern "C" {
-#endif
-
 /** \addtogroup ClassDriver_MSC
  *  @{
  * \defgroup MSC_Device Device
diff --git a/src/common/compiler/tusb_compiler_gcc.h b/src/common/compiler/tusb_compiler_gcc.h
index a3b84116f..bb2d0b56b 100644
--- a/src/common/compiler/tusb_compiler_gcc.h
+++ b/src/common/compiler/tusb_compiler_gcc.h
@@ -35,34 +35,25 @@
  extern "C" {
 #endif
 
-#define ALIGN_OF(x) __alignof__(x)
+#define ALIGN_OF(x)                __alignof__(x)
 
-/// This attribute specifies a minimum alignment for the variable or structure field, measured in bytes
+// Specifies a minimum alignment for the variable or structure field, measured in bytes
 #define ATTR_ALIGNED(Bytes)        __attribute__ ((aligned(Bytes)))
 
-/// Place variable in a specific section
+// Place variable in a specific section
 #define ATTR_SECTION(sec_name)      __attribute__ (( section(#sec_name) ))
 
-/// The packed attribute specifies that a variable or structure field should have
-/// the smallest possible alignment—one byte for a variable, and one bit for a field.
+// Packed struct/variable into smallest possible size
 #define ATTR_PACKED                __attribute__ ((packed))
 #define ATTR_PREPACKED
 
-/// This attribute inlines the function even if no optimization level is specified
-#define ATTR_ALWAYS_INLINE         __attribute__ ((always_inline))
-
-/// The deprecated attribute results in a warning if the function is used anywhere in the source file.
-/// This is useful when identifying functions that are expected to be removed in a future version of a program.
+// The deprecated attribute results in a warning if the function is used.
 #define ATTR_DEPRECATED(mess)      __attribute__ ((deprecated(mess)))
 
-/// The weak attribute causes the declaration to be emitted as a weak symbol rather than a global.
-/// This is primarily useful in defining library functions that can be overridden in user code
+// The weak attribute causes the declaration to be emitted as a weak symbol rather than a global.
 #define ATTR_WEAK                  __attribute__ ((weak))
 
-/// Warn if a caller of the function with this attribute does not use its return value.
-#define ATTR_WARN_UNUSED_RESULT    __attribute__ ((warn_unused_result))
-
-/// Function is meant to be possibly unused. GCC does not produce a warning for this function.
+// Function/Variable is meant to be possibly unused (thus no warning)
 #define ATTR_UNUSED                __attribute__ ((unused))
 
 // TODO mcu specific
diff --git a/src/common/compiler/tusb_compiler_iar.h b/src/common/compiler/tusb_compiler_iar.h
index 29bec875f..326a40031 100644
--- a/src/common/compiler/tusb_compiler_iar.h
+++ b/src/common/compiler/tusb_compiler_iar.h
@@ -36,12 +36,8 @@
 //#define ATTR_SECTION(section)      _Pragma((#section))
 #define ATTR_PREPACKED            __packed
 #define ATTR_PACKED
-
-#define ATTR_ALWAYS_INLINE
 #define ATTR_DEPRECATED(mess)
 #define ATTR_WEAK                 __weak
-
-#define ATTR_WARN_UNUSED_RESULT
 #define ATTR_UNUSED
 
 // built-in function to convert 32-bit Big-Endian to Little-Endian
@@ -52,6 +48,8 @@
 #define __n2be_16(u16)  ((uint16_t) __REV16(u16))
 #define __be2n_16(u16)  __n2be_16(u16)
 
+#error "IAR won't work due to '__packed' placement before struct"
+
 #ifdef __cplusplus
  }
 #endif
diff --git a/src/common/tusb_common.h b/src/common/tusb_common.h
index c877f0137..0b5a37922 100644
--- a/src/common/tusb_common.h
+++ b/src/common/tusb_common.h
@@ -113,7 +113,6 @@
 #include "tusb_option.h"
 #include "tusb_compiler.h"
 #include "tusb_verify.h"
-//#include "binary.h"
 #include "tusb_error.h"
 #include "tusb_timeout.h"
 #include "tusb_types.h"
diff --git a/src/common/tusb_types.h b/src/common/tusb_types.h
index 3a4ddb4c3..7d57a7950 100644
--- a/src/common/tusb_types.h
+++ b/src/common/tusb_types.h
@@ -127,25 +127,23 @@ typedef enum
 
 typedef enum
 {
-  TUSB_CLASS_UNSPECIFIED          = 0    , ///< 0
-  TUSB_CLASS_AUDIO                = 1    , ///< 1
-  TUSB_CLASS_CDC                  = 2    , ///< 2
-  TUSB_CLASS_HID                  = 3    , ///< 3
-  TUSB_CLASS_RESERVED_4           = 4    , ///< 4
-  TUSB_CLASS_PHYSICAL             = 5    , ///< 5
-  TUSB_CLASS_IMAGE                = 6    , ///< 6
-  TUSB_CLASS_PRINTER              = 7    , ///< 7
-  TUSB_CLASS_MSC                  = 8    , ///< 8
-  TUSB_CLASS_HUB                  = 9    , ///< 9
-  TUSB_CLASS_CDC_DATA             = 10   , ///< 10
-  TUSB_CLASS_SMART_CARD           = 11   , ///< 11
-  TUSB_CLASS_RESERVED_12          = 12   , ///< 12
-  TUSB_CLASS_CONTENT_SECURITY     = 13   , ///< 13
-  TUSB_CLASS_VIDEO                = 14   , ///< 14
-  TUSB_CLASS_PERSONAL_HEALTHCARE  = 15   , ///< 15
-  TUSB_CLASS_AUDIO_VIDEO          = 16   , ///< 16
-
-  TUSB_CLASS_MAPPED_INDEX_START   = 17   , // TODO Map DIAGNOSTIC, WIRELESS_CONTROLLER, MISC, VENDOR_SPECIFIC to this to minimize the array
+  TUSB_CLASS_UNSPECIFIED          = 0    ,
+  TUSB_CLASS_AUDIO                = 1    ,
+  TUSB_CLASS_CDC                  = 2    ,
+  TUSB_CLASS_HID                  = 3    ,
+  TUSB_CLASS_RESERVED_4           = 4    ,
+  TUSB_CLASS_PHYSICAL             = 5    ,
+  TUSB_CLASS_IMAGE                = 6    ,
+  TUSB_CLASS_PRINTER              = 7    ,
+  TUSB_CLASS_MSC                  = 8    ,
+  TUSB_CLASS_HUB                  = 9    ,
+  TUSB_CLASS_CDC_DATA             = 10   ,
+  TUSB_CLASS_SMART_CARD           = 11   ,
+  TUSB_CLASS_RESERVED_12          = 12   ,
+  TUSB_CLASS_CONTENT_SECURITY     = 13   ,
+  TUSB_CLASS_VIDEO                = 14   ,
+  TUSB_CLASS_PERSONAL_HEALTHCARE  = 15   ,
+  TUSB_CLASS_AUDIO_VIDEO          = 16   ,
 
   TUSB_CLASS_DIAGNOSTIC           = 0xDC ,
   TUSB_CLASS_WIRELESS_CONTROLLER  = 0xE0 ,
diff --git a/src/device/usbd_auto_desc.c b/src/device/usbd_auto_desc.c
index e418cd23c..4b683e354 100644
--- a/src/device/usbd_auto_desc.c
+++ b/src/device/usbd_auto_desc.c
@@ -43,7 +43,6 @@
 #endif
 
 #ifndef CFG_TUD_DESC_PID
-
 /* A combination of interfaces must have a unique product id, since PC will save device driver after the first plug.
  * Same VID/PID with different interface e.g MSC (first), then CDC (later) will possibly cause system error on PC.
  *
@@ -484,7 +483,7 @@ desc_auto_cfg_t const _desc_auto_config_struct =
           .bEndpointAddress = EP_MSC_OUT,
           .bmAttributes     = { .xfer = TUSB_XFER_BULK },
           .wMaxPacketSize   = { .size = EP_MSC_SIZE},
-          .bInterval        = 1
+          .bInterval        = 0
       },
 
       .ep_in =
@@ -494,7 +493,7 @@ desc_auto_cfg_t const _desc_auto_config_struct =
           .bEndpointAddress = EP_MSC_IN,
           .bmAttributes     = { .xfer = TUSB_XFER_BULK },
           .wMaxPacketSize   = { .size = EP_MSC_SIZE},
-          .bInterval        = 1
+          .bInterval        = 0
       }
     },
 #endif // msc