Merge remote-tracking branch 'tinyusb/master' into copilot/fix-dcd-edpt-xfer-issue

Signed-off-by: HiFiPhile <[email protected]>

11 files changed, 386 insertions, 193 deletions

diff --git a/examples/device/dfu/src/main.c b/examples/device/dfu/src/main.c
index c0c848837..77632bf1a 100644
--- a/examples/device/dfu/src/main.c
+++ b/examples/device/dfu/src/main.c
@@ -23,7 +23,7 @@
  *
  */
 
- /*
+/*
   * After device is enumerated in dfu mode run the following commands
   *
   * To transfer firmware from host to device (best to test with text file)
@@ -48,21 +48,18 @@
 //--------------------------------------------------------------------+
 // MACRO CONSTANT TYPEDEF PROTYPES
 //--------------------------------------------------------------------+
-const char* upload_image[2]=
-{
-  "Hello world from TinyUSB DFU! - Partition 0",
-  "Hello world from TinyUSB DFU! - Partition 1"
-};
+const char *upload_image[2] = {"Hello world from TinyUSB DFU! - Partition 0",
+                               "Hello world from TinyUSB DFU! - Partition 1"};
 
 /* Blink pattern
  * - 250 ms  : device not mounted
  * - 1000 ms : device mounted
  * - 2500 ms : device is suspended
  */
-enum  {
+enum {
   BLINK_NOT_MOUNTED = 250,
-  BLINK_MOUNTED = 1000,
-  BLINK_SUSPENDED = 2500,
+  BLINK_MOUNTED     = 1000,
+  BLINK_SUSPENDED   = 2500,
 };
 
 static uint32_t blink_interval_ms = BLINK_NOT_MOUNTED;
@@ -70,21 +67,16 @@ static uint32_t blink_interval_ms = BLINK_NOT_MOUNTED;
 void led_blinking_task(void);
 
 /*------------- MAIN -------------*/
-int main(void)
-{
+int main(void) {
   board_init();
 
   // init device stack on configured roothub port
-  tusb_rhport_init_t dev_init = {
-    .role = TUSB_ROLE_DEVICE,
-    .speed = TUSB_SPEED_AUTO
-  };
+  tusb_rhport_init_t dev_init = {.role = TUSB_ROLE_DEVICE, .speed = TUSB_SPEED_AUTO};
   tusb_init(BOARD_TUD_RHPORT, &dev_init);
 
   board_init_after_tusb();
 
-  while (1)
-  {
+  while (1) {
     tud_task(); // tinyusb device task
     led_blinking_task();
   }
@@ -95,29 +87,25 @@ int main(void)
 //--------------------------------------------------------------------+
 
 // Invoked when device is mounted
-void tud_mount_cb(void)
-{
+void tud_mount_cb(void) {
   blink_interval_ms = BLINK_MOUNTED;
 }
 
 // Invoked when device is unmounted
-void tud_umount_cb(void)
-{
+void tud_umount_cb(void) {
   blink_interval_ms = BLINK_NOT_MOUNTED;
 }
 
 // Invoked when usb bus is suspended
 // remote_wakeup_en : if host allow us  to perform remote wakeup
 // Within 7ms, device must draw an average of current less than 2.5 mA from bus
-void tud_suspend_cb(bool remote_wakeup_en)
-{
-  (void) remote_wakeup_en;
+void tud_suspend_cb(bool remote_wakeup_en) {
+  (void)remote_wakeup_en;
   blink_interval_ms = BLINK_SUSPENDED;
 }
 
 // Invoked when usb bus is resumed
-void tud_resume_cb(void)
-{
+void tud_resume_cb(void) {
   blink_interval_ms = tud_mounted() ? BLINK_MOUNTED : BLINK_NOT_MOUNTED;
 }
 
@@ -129,19 +117,17 @@ void tud_resume_cb(void)
 // Invoked right before tud_dfu_download_cb() (state=DFU_DNBUSY) or tud_dfu_manifest_cb() (state=DFU_MANIFEST)
 // Application return timeout in milliseconds (bwPollTimeout) for the next download/manifest operation.
 // During this period, USB host won't try to communicate with us.
-uint32_t tud_dfu_get_timeout_cb(uint8_t alt, uint8_t state)
-{
-  if ( state == DFU_DNBUSY )
-  {
+uint32_t tud_dfu_get_timeout_cb(uint8_t alt, uint8_t state) {
+  if (state == DFU_DNBUSY) {
     // For this example
     // - Atl0 Flash is fast : 1   ms
     // - Alt1 EEPROM is slow: 100 ms
     return (alt == 0) ? 1 : 100;
-  }
-  else if (state == DFU_MANIFEST)
-  {
+  } else if (state == DFU_MANIFEST) {
     // since we don't buffer entire image and do any flashing in manifest stage
     return 0;
+  } else {
+    // nothing to do
   }
 
   return 0;
@@ -150,15 +136,13 @@ uint32_t tud_dfu_get_timeout_cb(uint8_t alt, uint8_t state)
 // Invoked when received DFU_DNLOAD (wLength>0) following by DFU_GETSTATUS (state=DFU_DNBUSY) requests
 // This callback could be returned before flashing op is complete (async).
 // Once finished flashing, application must call tud_dfu_finish_flashing()
-void tud_dfu_download_cb(uint8_t alt, uint16_t block_num, uint8_t const* data, uint16_t length)
-{
-  (void) alt;
-  (void) block_num;
+void tud_dfu_download_cb(uint8_t alt, uint16_t block_num, const uint8_t *data, uint16_t length) {
+  (void)alt;
+  (void)block_num;
 
   //printf("\r\nReceived Alt %u BlockNum %u of length %u\r\n", alt, wBlockNum, length);
 
-  for(uint16_t i=0; i<length; i++)
-  {
+  for (uint16_t i = 0; i < length; i++) {
     printf("%c", data[i]);
   }
 
@@ -169,9 +153,8 @@ void tud_dfu_download_cb(uint8_t alt, uint16_t block_num, uint8_t const* data, u
 // Invoked when download process is complete, received DFU_DNLOAD (wLength=0) following by DFU_GETSTATUS (state=Manifest)
 // Application can do checksum, or actual flashing if buffered entire image previously.
 // Once finished flashing, application must call tud_dfu_finish_flashing()
-void tud_dfu_manifest_cb(uint8_t alt)
-{
-  (void) alt;
+void tud_dfu_manifest_cb(uint8_t alt) {
+  (void)alt;
   printf("Download completed, enter manifestation\r\n");
 
   // flashing op for manifest is complete without error
@@ -182,27 +165,28 @@ void tud_dfu_manifest_cb(uint8_t alt)
 // Invoked when received DFU_UPLOAD request
 // Application must populate data with up to length bytes and
 // Return the number of written bytes
-uint16_t tud_dfu_upload_cb(uint8_t alt, uint16_t block_num, uint8_t* data, uint16_t length)
-{
-  (void) block_num;
-  (void) length;
+uint16_t tud_dfu_upload_cb(uint8_t alt, uint16_t block_num, uint8_t *data, uint16_t length) {
+  (void)block_num;
+  (void)length;
 
-  uint16_t const xfer_len = (uint16_t) strlen(upload_image[alt]);
+  if (block_num != 0u) {
+    return 0; // for this example we only support single block upload
+  }
+
+  const uint16_t xfer_len = tu_min16((uint16_t)strlen(upload_image[alt]), length);
   memcpy(data, upload_image[alt], xfer_len);
 
   return xfer_len;
 }
 
 // Invoked when the Host has terminated a download or upload transfer
-void tud_dfu_abort_cb(uint8_t alt)
-{
-  (void) alt;
+void tud_dfu_abort_cb(uint8_t alt) {
+  (void)alt;
   printf("Host aborted transfer\r\n");
 }
 
 // Invoked when a DFU_DETACH request is received
-void tud_dfu_detach_cb(void)
-{
+void tud_dfu_detach_cb(void) {
   printf("Host detach, we should probably reboot\r\n");
 }
 
@@ -210,13 +194,14 @@ void tud_dfu_detach_cb(void)
 // BLINKING TASK + Indicator pulse
 //--------------------------------------------------------------------+
 
-void led_blinking_task(void)
-{
-  static uint32_t start_ms = 0;
-  static bool led_state = false;
+void led_blinking_task(void) {
+  static uint32_t start_ms  = 0;
+  static bool     led_state = false;
 
   // Blink every interval ms
-  if ( board_millis() - start_ms < blink_interval_ms) return; // not enough time
+  if (board_millis() - start_ms < blink_interval_ms) {
+    return; // not enough time
+  }
   start_ms += blink_interval_ms;
 
   board_led_write(led_state);
diff --git a/examples/device/dfu/src/usb_descriptors.c b/examples/device/dfu/src/usb_descriptors.c
index 48c9985f3..e4291be2d 100644
--- a/examples/device/dfu/src/usb_descriptors.c
+++ b/examples/device/dfu/src/usb_descriptors.c
@@ -25,7 +25,6 @@
 
 #include "bsp/board_api.h"
 #include "tusb.h"
-#include "class/dfu/dfu_device.h"
 
 /* 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.
@@ -33,49 +32,45 @@
  * Auto ProductID layout's Bitmap:
  *   [MSB]         HID | MSC | CDC          [LSB]
  */
-#define PID_MAP(itf, n)  ((CFG_TUD_##itf) ? (1 << (n)) : 0)
-#define USB_PID           (0x4000 | PID_MAP(CDC, 0) | PID_MAP(MSC, 1) | PID_MAP(HID, 2) | \
-                           PID_MAP(MIDI, 3) | PID_MAP(VENDOR, 4) )
+#define PID_MAP(itf, n) ((CFG_TUD_##itf) ? (1 << (n)) : 0)
+#define USB_PID         (0x4000 | PID_MAP(CDC, 0) | PID_MAP(MSC, 1) | PID_MAP(HID, 2) | PID_MAP(MIDI, 3) | PID_MAP(VENDOR, 4))
 
 //--------------------------------------------------------------------+
 // Device Descriptors
 //--------------------------------------------------------------------+
-static tusb_desc_device_t const desc_device =
-{
-    .bLength            = sizeof(tusb_desc_device_t),
-    .bDescriptorType    = TUSB_DESC_DEVICE,
-    .bcdUSB             = 0x0200,
+static const tusb_desc_device_t desc_device =
+  {.bLength         = sizeof(tusb_desc_device_t),
+   .bDescriptorType = TUSB_DESC_DEVICE,
+   .bcdUSB          = 0x0201,
 
-  #if CFG_TUD_CDC
-    // Use Interface Association Descriptor (IAD) for CDC
-    // As required by USB Specs IAD's subclass must be common class (2) and protocol must be IAD (1)
-    .bDeviceClass       = TUSB_CLASS_MISC,
-    .bDeviceSubClass    = MISC_SUBCLASS_COMMON,
-    .bDeviceProtocol    = MISC_PROTOCOL_IAD,
-  #else
-    .bDeviceClass       = 0x00,
-    .bDeviceSubClass    = 0x00,
-    .bDeviceProtocol    = 0x00,
-  #endif
+#if CFG_TUD_CDC
+   // Use Interface Association Descriptor (IAD) for CDC
+   // As required by USB Specs IAD's subclass must be common class (2) and protocol must be IAD (1)
+   .bDeviceClass    = TUSB_CLASS_MISC,
+   .bDeviceSubClass = MISC_SUBCLASS_COMMON,
+   .bDeviceProtocol = MISC_PROTOCOL_IAD,
+#else
+   .bDeviceClass    = 0x00,
+   .bDeviceSubClass = 0x00,
+   .bDeviceProtocol = 0x00,
+#endif
 
-    .bMaxPacketSize0    = CFG_TUD_ENDPOINT0_SIZE,
+   .bMaxPacketSize0 = CFG_TUD_ENDPOINT0_SIZE,
 
-    .idVendor           = 0xCafe,
-    .idProduct          = USB_PID,
-    .bcdDevice          = 0x0100,
+   .idVendor  = 0xCafe,
+   .idProduct = USB_PID,
+   .bcdDevice = 0x0100,
 
-    .iManufacturer      = 0x01,
-    .iProduct           = 0x02,
-    .iSerialNumber      = 0x03,
+   .iManufacturer = 0x01,
+   .iProduct      = 0x02,
+   .iSerialNumber = 0x03,
 
-    .bNumConfigurations = 0x01
-};
+   .bNumConfigurations = 0x01};
 
 // Invoked when received GET DEVICE DESCRIPTOR
 // Application return pointer to descriptor
-uint8_t const * tud_descriptor_device_cb(void)
-{
-  return (uint8_t const *) &desc_device;
+const uint8_t *tud_descriptor_device_cb(void) {
+  return (const uint8_t *)&desc_device;
 }
 
 //--------------------------------------------------------------------+
@@ -83,20 +78,17 @@ uint8_t const * tud_descriptor_device_cb(void)
 //--------------------------------------------------------------------+
 
 // Number of Alternate Interface (each for 1 flash partition)
-#define ALT_COUNT   2
+#define ALT_COUNT 2
 
-enum
-{
+enum {
   ITF_NUM_DFU_MODE,
   ITF_NUM_TOTAL
 };
 
-#define CONFIG_TOTAL_LEN    (TUD_CONFIG_DESC_LEN + TUD_DFU_DESC_LEN(ALT_COUNT))
-
-#define FUNC_ATTRS (DFU_ATTR_CAN_UPLOAD | DFU_ATTR_CAN_DOWNLOAD | DFU_ATTR_MANIFESTATION_TOLERANT)
+#define CONFIG_TOTAL_LEN (TUD_CONFIG_DESC_LEN + TUD_DFU_DESC_LEN(ALT_COUNT))
+#define FUNC_ATTRS       (DFU_ATTR_CAN_UPLOAD | DFU_ATTR_CAN_DOWNLOAD | DFU_ATTR_MANIFESTATION_TOLERANT)
 
-uint8_t const desc_configuration[] =
-{
+uint8_t const desc_configuration[] = {
   // Config number, interface count, string index, total length, attribute, power in mA
   TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, 0x00, 100),
 
@@ -107,13 +99,91 @@ uint8_t const desc_configuration[] =
 // Invoked when received GET CONFIGURATION DESCRIPTOR
 // Application return pointer to descriptor
 // Descriptor contents must exist long enough for transfer to complete
-uint8_t const * tud_descriptor_configuration_cb(uint8_t index)
-{
-  (void) index; // for multiple configurations
+const uint8_t *tud_descriptor_configuration_cb(uint8_t index) {
+  (void)index; // for multiple configurations
   return desc_configuration;
 }
 
 //--------------------------------------------------------------------+
+// BOS Descriptor
+//--------------------------------------------------------------------+
+
+/* Microsoft OS 2.0 registry property descriptor
+  Per MS requirements https://msdn.microsoft.com/en-us/library/windows/hardware/hh450799(v=vs.85).aspx
+  device should create DeviceInterfaceGUIDs. It can be done by driver and
+  in case of real PnP solution device should expose MS "Microsoft OS 2.0
+  registry property descriptor". Such descriptor can insert any record
+  into Windows registry per device/configuration/interface. In our case it
+  will insert "DeviceInterfaceGUIDs" multistring property.
+  GUID is freshly generated and should be OK to use.
+  https://developers.google.com/web/fundamentals/native-hardware/build-for-webusb/
+  (Section Microsoft OS compatibility descriptors)
+*/
+
+#define BOS_TOTAL_LEN            (TUD_BOS_DESC_LEN + TUD_BOS_MICROSOFT_OS_DESC_LEN)
+#define MS_OS_20_DESC_LEN        0xA2
+#define VENDOR_REQUEST_MICROSOFT 1
+
+// BOS Descriptor is required for webUSB
+const uint8_t desc_bos[] = {
+  // total length, number of device caps
+  TUD_BOS_DESCRIPTOR(BOS_TOTAL_LEN, 1),
+
+  // Microsoft OS 2.0 descriptor
+  TUD_BOS_MS_OS_20_DESCRIPTOR(MS_OS_20_DESC_LEN, 1)};
+
+const uint8_t *tud_descriptor_bos_cb(void) {
+  return desc_bos;
+}
+
+const uint8_t desc_ms_os_20[] = {
+  // Set header: length, type, windows version, total length
+  U16_TO_U8S_LE(0x000A), U16_TO_U8S_LE(MS_OS_20_SET_HEADER_DESCRIPTOR), U32_TO_U8S_LE(0x06030000),
+  U16_TO_U8S_LE(MS_OS_20_DESC_LEN),
+
+  // MS OS 2.0 Compatible ID descriptor: length, type, compatible ID, sub compatible ID
+  U16_TO_U8S_LE(0x0014), U16_TO_U8S_LE(MS_OS_20_FEATURE_COMPATBLE_ID), 'W', 'I', 'N', 'U', 'S', 'B', 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // sub-compatible
+
+  // MS OS 2.0 Registry property descriptor: length, type
+  U16_TO_U8S_LE(MS_OS_20_DESC_LEN - 0x0A - 0x14), U16_TO_U8S_LE(MS_OS_20_FEATURE_REG_PROPERTY),
+  U16_TO_U8S_LE(0x0007), U16_TO_U8S_LE(0x002A),// wPropertyDataType, wPropertyNameLength and PropertyName "DeviceInterfaceGUIDs\0" in UTF-16
+  'D', 0x00, 'e', 0x00, 'v', 0x00, 'i', 0x00, 'c', 0x00, 'e', 0x00, 'I', 0x00, 'n', 0x00, 't', 0x00, 'e', 0x00,
+  'r', 0x00, 'f', 0x00, 'a', 0x00, 'c', 0x00, 'e', 0x00, 'G', 0x00, 'U', 0x00, 'I', 0x00, 'D', 0x00, 's', 0x00, 0x00, 0x00,
+  U16_TO_U8S_LE(0x0050),// wPropertyDataLength
+  //bPropertyData: {3E7E0711-DF3B-4158-A32F-E5951B2AB9A1}.
+  '{', 0x00, '3', 0x00, 'E', 0x00, '7', 0x00, 'E', 0x00, '0', 0x00, '7', 0x00, '1', 0x00, '1', 0x00, '-', 0x00,
+  'D', 0x00, 'F', 0x00, '3', 0x00, 'B', 0x00, '-', 0x00, '4', 0x00, '1', 0x00, '5', 0x00, '8', 0x00, '-', 0x00,
+  'A', 0x00, '3', 0x00, '2', 0x00, 'F', 0x00, '-', 0x00, 'E', 0x00, '5', 0x00, '9', 0x00, '5', 0x00, '1', 0x00,
+  'B', 0x00, '2', 0x00, 'A', 0x00, 'B', 0x00, '9', 0x00, 'A', 0x00, '1', 0x00, '}', 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+TU_VERIFY_STATIC(sizeof(desc_ms_os_20) == MS_OS_20_DESC_LEN, "Incorrect size");
+
+// Invoked when a control transfer occurred on an interface of this class
+// Driver response accordingly to the request and the transfer stage (setup/data/ack)
+// return false to stall control endpoint (e.g unsupported request)
+bool tud_vendor_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_request_t *request) {
+  // nothing to with DATA & ACK stage
+  if (stage != CONTROL_STAGE_SETUP) {
+    return true;
+  }
+
+  if (request->bmRequestType_bit.type == TUSB_REQ_TYPE_VENDOR) {
+    if (request->bRequest == VENDOR_REQUEST_MICROSOFT) {
+      if (request->wIndex == 7) {
+        return tud_control_xfer(rhport, request, (void *)(uintptr_t)desc_ms_os_20, MS_OS_20_DESC_LEN);
+      } else {
+        return false;
+      }
+    }
+  }
+
+  // stall unknown request
+  return false;
+}
+
+//--------------------------------------------------------------------+
 // String Descriptors
 //--------------------------------------------------------------------+
 
@@ -126,25 +196,24 @@ enum {
 };
 
 // array of pointer to string descriptors
-static char const *string_desc_arr[] =
-{
-  (const char[]) { 0x09, 0x04 }, // 0: is supported language is English (0x0409)
-  "TinyUSB",                     // 1: Manufacturer
-  "TinyUSB Device",              // 2: Product
-  NULL,                          // 3: Serials will use unique ID if possible
-  "FLASH",                       // 4: DFU Partition 1
-  "EEPROM",                      // 5: DFU Partition 2
+static const char *string_desc_arr[] = {
+  (const char[]){0x09, 0x04}, // 0: is supported language is English (0x0409)
+  "TinyUSB",                  // 1: Manufacturer
+  "TinyUSB Device",           // 2: Product
+  NULL,                       // 3: Serials will use unique ID if possible
+  "FLASH",                    // 4: DFU Partition 1
+  "EEPROM",                   // 5: DFU Partition 2
 };
 
 static uint16_t _desc_str[32 + 1];
 
 // Invoked when received GET STRING DESCRIPTOR request
 // Application return pointer to descriptor, whose contents must exist long enough for transfer to complete
-uint16_t const *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
-  (void) langid;
+const uint16_t *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
+  (void)langid;
   size_t chr_count;
 
-  switch ( index ) {
+  switch (index) {
     case STRID_LANGID:
       memcpy(&_desc_str[1], string_desc_arr[0], 2);
       chr_count = 1;
@@ -165,21 +234,21 @@ uint16_t const *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
       const char *str = string_desc_arr[index];
 
       // Cap at max char
-      chr_count = strlen(str);
-      size_t const max_count = sizeof(_desc_str) / sizeof(_desc_str[0]) - 1; // -1 for string type
+      chr_count              = strlen(str);
+      const size_t max_count = sizeof(_desc_str) / sizeof(_desc_str[0]) - 1; // -1 for string type
       if (chr_count > max_count) {
         chr_count = max_count;
       }
 
       // Convert ASCII string into UTF-16
-      for ( size_t i = 0; i < chr_count; i++ ) {
+      for (size_t i = 0; i < chr_count; i++) {
         _desc_str[1 + i] = str[i];
       }
       break;
   }
 
   // first byte is length (including header), second byte is string type
-  _desc_str[0] = (uint16_t) ((TUSB_DESC_STRING << 8) | (2 * chr_count + 2));
+  _desc_str[0] = (uint16_t)((TUSB_DESC_STRING << 8) | (2 * chr_count + 2));
 
   return _desc_str;
 }
diff --git a/examples/device/dfu_runtime/src/usb_descriptors.c b/examples/device/dfu_runtime/src/usb_descriptors.c
index 5d5cf52cd..8fa078da2 100644
--- a/examples/device/dfu_runtime/src/usb_descriptors.c
+++ b/examples/device/dfu_runtime/src/usb_descriptors.c
@@ -25,7 +25,6 @@
 
 #include "bsp/board_api.h"
 #include "tusb.h"
-#include "class/dfu/dfu_rt_device.h"
 
 /* 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.
@@ -33,48 +32,45 @@
  * Auto ProductID layout's Bitmap:
  *   [MSB]         HID | MSC | CDC          [LSB]
  */
-#define PID_MAP(itf, n)  ((CFG_TUD_##itf) ? (1 << (n)) : 0)
-#define USB_PID           (0x4000 | PID_MAP(CDC, 0) | PID_MAP(MSC, 1) | PID_MAP(HID, 2) | \
-                           PID_MAP(MIDI, 3) | PID_MAP(VENDOR, 4) )
+#define PID_MAP(itf, n) ((CFG_TUD_##itf) ? (1 << (n)) : 0)
+#define USB_PID         (0x4000 | PID_MAP(CDC, 0) | PID_MAP(MSC, 1) | PID_MAP(HID, 2) | PID_MAP(MIDI, 3) | PID_MAP(VENDOR, 4))
 
 //--------------------------------------------------------------------+
 // Device Descriptors
 //--------------------------------------------------------------------+
-static tusb_desc_device_t const desc_device =
-{
-    .bLength            = sizeof(tusb_desc_device_t),
-    .bDescriptorType    = TUSB_DESC_DEVICE,
-    .bcdUSB             = 0x0200,
+static const tusb_desc_device_t desc_device = {
+  .bLength = sizeof(tusb_desc_device_t),
+  .bDescriptorType = TUSB_DESC_DEVICE,
+  .bcdUSB = 0x0201,
 
-  #if CFG_TUD_CDC
-    // Use Interface Association Descriptor (IAD) for CDC
-    // As required by USB Specs IAD's subclass must be common class (2) and protocol must be IAD (1)
-    .bDeviceClass       = TUSB_CLASS_MISC,
-    .bDeviceSubClass    = MISC_SUBCLASS_COMMON,
-    .bDeviceProtocol    = MISC_PROTOCOL_IAD,
-  #else
-    .bDeviceClass       = 0x00,
-    .bDeviceSubClass    = 0x00,
-    .bDeviceProtocol    = 0x00,
-  #endif
+#if CFG_TUD_CDC
+  // Use Interface Association Descriptor (IAD) for CDC
+  // As required by USB Specs IAD's subclass must be common class (2) and protocol must be IAD (1)
+  .bDeviceClass = TUSB_CLASS_MISC,
+  .bDeviceSubClass = MISC_SUBCLASS_COMMON,
+  .bDeviceProtocol = MISC_PROTOCOL_IAD,
+#else
+  .bDeviceClass = 0x00,
+  .bDeviceSubClass = 0x00,
+  .bDeviceProtocol = 0x00,
+#endif
 
-    .bMaxPacketSize0    = CFG_TUD_ENDPOINT0_SIZE,
+  .bMaxPacketSize0 = CFG_TUD_ENDPOINT0_SIZE,
 
-    .idVendor           = 0xCafe,
-    .idProduct          = USB_PID,
-    .bcdDevice          = 0x0100,
+  .idVendor = 0xCafe,
+  .idProduct = USB_PID,
+  .bcdDevice = 0x0100,
 
-    .iManufacturer      = 0x01,
-    .iProduct           = 0x02,
-    .iSerialNumber      = 0x03,
+  .iManufacturer = 0x01,
+  .iProduct = 0x02,
+  .iSerialNumber = 0x03,
 
-    .bNumConfigurations = 0x01
+  .bNumConfigurations = 0x01
 };
 
 // Invoked when received GET DEVICE DESCRIPTOR
 // Application return pointer to descriptor
-uint8_t const * tud_descriptor_device_cb(void)
-{
+uint8_t const *tud_descriptor_device_cb(void) {
   return (uint8_t const *) &desc_device;
 }
 
@@ -82,16 +78,14 @@ uint8_t const * tud_descriptor_device_cb(void)
 // Configuration Descriptor
 //--------------------------------------------------------------------+
 
-enum
-{
+enum {
   ITF_NUM_DFU_RT,
   ITF_NUM_TOTAL
 };
 
-#define CONFIG_TOTAL_LEN    (TUD_CONFIG_DESC_LEN + TUD_DFU_RT_DESC_LEN)
+#define CONFIG_TOTAL_LEN (TUD_CONFIG_DESC_LEN + TUD_DFU_RT_DESC_LEN)
 
-uint8_t const desc_configuration[] =
-{
+uint8_t const desc_configuration[] = {
   // Config number, interface count, string index, total length, attribute, power in mA
   TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, 0x00, 100),
 
@@ -103,13 +97,109 @@ uint8_t const desc_configuration[] =
 // Invoked when received GET CONFIGURATION DESCRIPTOR
 // Application return pointer to descriptor
 // Descriptor contents must exist long enough for transfer to complete
-uint8_t const * tud_descriptor_configuration_cb(uint8_t index)
-{
-  (void) index; // for multiple configurations
+uint8_t const *tud_descriptor_configuration_cb(uint8_t index) {
+  (void) index;// for multiple configurations
   return desc_configuration;
 }
 
 //--------------------------------------------------------------------+
+// BOS Descriptor
+//--------------------------------------------------------------------+
+
+/* Microsoft OS 2.0 registry property descriptor
+  Per MS requirements https://msdn.microsoft.com/en-us/library/windows/hardware/hh450799(v=vs.85).aspx
+  device should create DeviceInterfaceGUIDs. It can be done by driver and
+  in case of real PnP solution device should expose MS "Microsoft OS 2.0
+  registry property descriptor". Such descriptor can insert any record
+  into Windows registry per device/configuration/interface. In our case it
+  will insert "DeviceInterfaceGUIDs" multistring property.
+  GUID is freshly generated and should be OK to use.
+  https://developers.google.com/web/fundamentals/native-hardware/build-for-webusb/
+  (Section Microsoft OS compatibility descriptors)
+*/
+
+#define BOS_TOTAL_LEN (TUD_BOS_DESC_LEN + TUD_BOS_MICROSOFT_OS_DESC_LEN)
+#define MS_OS_20_DESC_LEN 0xA2
+#define VENDOR_REQUEST_MICROSOFT 1
+
+// BOS Descriptor is required for webUSB
+const uint8_t desc_bos[] = {
+  // total length, number of device caps
+  TUD_BOS_DESCRIPTOR(BOS_TOTAL_LEN, 1),
+
+  // Microsoft OS 2.0 descriptor
+  TUD_BOS_MS_OS_20_DESCRIPTOR(MS_OS_20_DESC_LEN, 1)};
+
+const uint8_t *tud_descriptor_bos_cb(void) {
+  return desc_bos;
+}
+
+uint8_t const desc_ms_os_20[] = {
+    // Set header: length, type, windows version, total length
+    U16_TO_U8S_LE(0x000A), U16_TO_U8S_LE(MS_OS_20_SET_HEADER_DESCRIPTOR), U32_TO_U8S_LE(0x06030000), U16_TO_U8S_LE(MS_OS_20_DESC_LEN),
+
+    // MS OS 2.0 Compatible ID descriptor: length, type, compatible ID, sub compatible ID
+    U16_TO_U8S_LE(0x0014), U16_TO_U8S_LE(MS_OS_20_FEATURE_COMPATBLE_ID), 'W', 'I', 'N', 'U', 'S', 'B', 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,// sub-compatible
+
+    // MS OS 2.0 Registry property descriptor: length, type
+    U16_TO_U8S_LE(MS_OS_20_DESC_LEN - 0x0A - 0x14), U16_TO_U8S_LE(MS_OS_20_FEATURE_REG_PROPERTY),
+    U16_TO_U8S_LE(0x0007), U16_TO_U8S_LE(0x002A),// wPropertyDataType, wPropertyNameLength and PropertyName "DeviceInterfaceGUIDs\0" in UTF-16
+    'D', 0x00, 'e', 0x00, 'v', 0x00, 'i', 0x00, 'c', 0x00, 'e', 0x00, 'I', 0x00, 'n', 0x00, 't', 0x00, 'e', 0x00,
+    'r', 0x00, 'f', 0x00, 'a', 0x00, 'c', 0x00, 'e', 0x00, 'G', 0x00, 'U', 0x00, 'I', 0x00, 'D', 0x00, 's', 0x00, 0x00, 0x00,
+    U16_TO_U8S_LE(0x0050),// wPropertyDataLength
+    //bPropertyData: {F7CC2C68-3B14-4D72-B876-1A981AD2C9E5}.
+    '{', 0x00, 'F', 0x00, '7', 0x00, 'C', 0x00, 'C', 0x00, '2', 0x00, 'C', 0x00, '6', 0x00, '8', 0x00, '-', 0x00,
+    '3', 0x00, 'B', 0x00, '1', 0x00, '4', 0x00, '-', 0x00, '4', 0x00, 'D', 0x00, '7', 0x00, '2', 0x00, '-', 0x00,
+    'B', 0x00, '8', 0x00, '7', 0x00, '6', 0x00, '-', 0x00, '1', 0x00, 'A', 0x00, '9', 0x00, '8', 0x00, '1', 0x00,
+    'A', 0x00, 'D', 0x00, '2', 0x00, 'C', 0x00, '9', 0x00, 'E', 0x00, '5', 0x00, '}', 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+TU_VERIFY_STATIC(sizeof(desc_ms_os_20) == MS_OS_20_DESC_LEN, "Incorrect size");
+
+// Invoked when a control transfer occurred on an interface of this class
+// Driver response accordingly to the request and the transfer stage (setup/data/ack)
+// return false to stall control endpoint (e.g unsupported request)
+bool tud_vendor_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const *request) {
+  // nothing to with DATA & ACK stage
+  if (stage != CONTROL_STAGE_SETUP) {
+    return true;
+  }
+
+  if (request->bmRequestType_bit.type == TUSB_REQ_TYPE_VENDOR) {
+    if (request->bRequest == VENDOR_REQUEST_MICROSOFT) {
+      if (request->wIndex == 7) {
+        return tud_control_xfer(rhport, request, (void *)(uintptr_t)desc_ms_os_20, MS_OS_20_DESC_LEN);
+      } else {
+        return false;
+      }
+    }
+  }
+
+  switch (request->bmRequestType_bit.type) {
+    case TUSB_REQ_TYPE_VENDOR:
+      switch (request->bRequest) {
+        case VENDOR_REQUEST_MICROSOFT:
+          if (request->wIndex == 7) {
+            return tud_control_xfer(rhport, request, (void *) (uintptr_t) desc_ms_os_20, MS_OS_20_DESC_LEN);
+          } else {
+            return false;
+          }
+
+        default:
+          break;
+      }
+      break;
+
+    default:
+      break;
+  }
+
+  // stall unknown request
+  return false;
+}
+
+//--------------------------------------------------------------------+
 // String Descriptors
 //--------------------------------------------------------------------+
 
@@ -122,24 +212,23 @@ enum {
 };
 
 // array of pointer to string descriptors
-static char const *string_desc_arr[] =
-{
-  (const char[]) { 0x09, 0x04 }, // 0: is supported language is English (0x0409)
-  "TinyUSB",                     // 1: Manufacturer
-  "TinyUSB Device",              // 2: Product
-  NULL,                          // 3: Serials will use unique ID if possible
-  "TinyUSB DFU runtime",         // 4: DFU runtime
+static char const *string_desc_arr[] = {
+  (const char[]){0x09, 0x04},// 0: is supported language is English (0x0409)
+  "TinyUSB",                 // 1: Manufacturer
+  "TinyUSB Device",          // 2: Product
+  NULL,                      // 3: Serials will use unique ID if possible
+  "TinyUSB DFU runtime",     // 4: DFU runtime
 };
 
 static uint16_t _desc_str[32 + 1];
 
 // Invoked when received GET STRING DESCRIPTOR request
 // Application return pointer to descriptor, whose contents must exist long enough for transfer to complete
-uint16_t const *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
-  (void) langid;
+const uint16_t *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
+  (void)langid;
   size_t chr_count;
 
-  switch ( index ) {
+  switch (index) {
     case STRID_LANGID:
       memcpy(&_desc_str[1], string_desc_arr[0], 2);
       chr_count = 1;
@@ -160,21 +249,21 @@ uint16_t const *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
       const char *str = string_desc_arr[index];
 
       // Cap at max char
-      chr_count = strlen(str);
-      size_t const max_count = sizeof(_desc_str) / sizeof(_desc_str[0]) - 1; // -1 for string type
+      chr_count              = strlen(str);
+      const size_t max_count = sizeof(_desc_str) / sizeof(_desc_str[0]) - 1; // -1 for string type
       if (chr_count > max_count) {
         chr_count = max_count;
       }
 
       // Convert ASCII string into UTF-16
-      for ( size_t i = 0; i < chr_count; i++ ) {
+      for (size_t i = 0; i < chr_count; i++) {
         _desc_str[1 + i] = str[i];
       }
       break;
   }
 
   // first byte is length (including header), second byte is string type
-  _desc_str[0] = (uint16_t) ((TUSB_DESC_STRING << 8) | (2 * chr_count + 2));
+  _desc_str[0] = (uint16_t)((TUSB_DESC_STRING << 8) | (2 * chr_count + 2));
 
   return _desc_str;
 }
diff --git a/examples/device/net_lwip_webserver/src/usb_descriptors.c b/examples/device/net_lwip_webserver/src/usb_descriptors.c
index b49962d65..c976cb62b 100644
--- a/examples/device/net_lwip_webserver/src/usb_descriptors.c
+++ b/examples/device/net_lwip_webserver/src/usb_descriptors.c
@@ -270,7 +270,7 @@ bool tud_vendor_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_contro
 
   switch (request->bmRequestType_bit.type) {
     case TUSB_REQ_TYPE_VENDOR:
-      switch (request->bRequest) { //-V2520 //-V2659
+      switch (request->bRequest) {
         case 1:
           if (request->wIndex == 7) {
             // Get Microsoft OS 2.0 compatible descriptor
diff --git a/examples/device/video_capture/skip.txt b/examples/device/video_capture/skip.txt
index 50302c544..cb0c7d2e6 100644
--- a/examples/device/video_capture/skip.txt
+++ b/examples/device/video_capture/skip.txt
@@ -1,6 +1,5 @@
 mcu:CH32V103
 mcu:CH32V20X
-mcu:MCXA15
 mcu:MSP430x5xx
 mcu:NUC121
 mcu:SAMD11
diff --git a/examples/device/video_capture/src/main.c b/examples/device/video_capture/src/main.c
index adcfb9f95..ffa2a7afa 100644
--- a/examples/device/video_capture/src/main.c
+++ b/examples/device/video_capture/src/main.c
@@ -56,6 +56,20 @@ void video_task(void* param);
 void freertos_init(void);
 #endif
 
+#if !defined(CFG_EXAMPLE_VIDEO_READONLY) || defined(CFG_EXAMPLE_VIDEO_BUFFERLESS)
+/* EBU color bars: https://stackoverflow.com/questions/6939422 */
+static uint8_t const bar_color[8][4] = {
+  /*  Y,   U,   Y,   V */
+  { 235, 128, 235, 128}, /* 100% White */
+  { 219,  16, 219, 138}, /* Yellow */
+  { 188, 154, 188,  16}, /* Cyan */
+  { 173,  42, 173,  26}, /* Green */
+  {  78, 214,  78, 230}, /* Magenta */
+  {  63, 102,  63, 240}, /* Red */
+  {  32, 240,  32, 118}, /* Blue */
+  {  16, 128,  16, 128}, /* Black */
+};
+#endif
 
 //--------------------------------------------------------------------+
 // Main
@@ -111,12 +125,43 @@ void tud_resume_cb(void) {
   blink_interval_ms = tud_mounted() ? BLINK_MOUNTED : BLINK_NOT_MOUNTED;
 }
 
+#ifdef CFG_EXAMPLE_VIDEO_BUFFERLESS
+
+#ifndef CFG_EXAMPLE_VIDEO_DISABLE_MJPEG
+  #error Demo only supports YUV2 please define CFG_EXAMPLE_VIDEO_DISABLE_MJPEG
+#endif
+
+void tud_video_prepare_payload_cb(uint_fast8_t ctl_idx, uint_fast8_t stm_idx, tud_video_payload_request_t* request)
+{
+  static uint32_t frame_counter = 0;
+  (void)ctl_idx;
+  (void)stm_idx;
+
+  /* Offset will be zero at the start of a new frame */
+  if (!request->offset) frame_counter++;
+
+  for (size_t buf_pos = 0; buf_pos < request->length; buf_pos += 2) {
+
+    /* Position within the current line (pixel relative) */
+    int line_pos = ((request->offset + buf_pos)>>1) % FRAME_WIDTH;
+
+    /* Choose color based on the position and change the table offset every 4 frames */
+    const uint8_t* color = bar_color[(line_pos/(FRAME_WIDTH / 8) + (frame_counter>>2)) % 8];
+
+    /* Copy pixel data for odd or even pixels */
+    memcpy(&((uint8_t*)request->buf)[buf_pos], &color[(line_pos & 1) ? 2 : 0], 2);
+  }
+
+}
+#endif
+
 //--------------------------------------------------------------------+
 // USB Video
 //--------------------------------------------------------------------+
 static unsigned frame_num = 0;
 static unsigned tx_busy = 0;
 static unsigned interval_ms = 1000 / FRAME_RATE;
+#ifndef CFG_EXAMPLE_VIDEO_BUFFERLESS
 
 #ifdef CFG_EXAMPLE_VIDEO_READONLY
 // For mcus that does not have enough SRAM for frame buffer, we use fixed frame data.
@@ -145,18 +190,6 @@ static struct {
 static uint8_t frame_buffer[FRAME_WIDTH * FRAME_HEIGHT * 16 / 8];
 
 static void fill_color_bar(uint8_t* buffer, unsigned start_position) {
-  /* EBU color bars: https://stackoverflow.com/questions/6939422 */
-  static uint8_t const bar_color[8][4] = {
-      /*  Y,   U,   Y,   V */
-      { 235, 128, 235, 128}, /* 100% White */
-      { 219,  16, 219, 138}, /* Yellow */
-      { 188, 154, 188,  16}, /* Cyan */
-      { 173,  42, 173,  26}, /* Green */
-      {  78, 214,  78, 230}, /* Magenta */
-      {  63, 102,  63, 240}, /* Red */
-      {  32, 240,  32, 118}, /* Blue */
-      {  16, 128,  16, 128}, /* Black */
-  };
   uint8_t* p;
 
   /* Generate the 1st line */
@@ -183,6 +216,8 @@ static void fill_color_bar(uint8_t* buffer, unsigned start_position) {
 
 #endif
 
+#endif /* NDEF CFG_EXAMPLE_VIDEO_BUFFERLESS */
+
 static void video_send_frame(void) {
   static unsigned start_ms = 0;
   static unsigned already_sent = 0;
@@ -197,7 +232,9 @@ static void video_send_frame(void) {
     already_sent = 1;
     tx_busy = 1;
     start_ms = board_millis();
-#ifdef CFG_EXAMPLE_VIDEO_READONLY
+#if defined(CFG_EXAMPLE_VIDEO_BUFFERLESS)
+    tud_video_n_frame_xfer(0, 0, NULL, FRAME_WIDTH * FRAME_HEIGHT * 16 / 8);
+#elif defined (CFG_EXAMPLE_VIDEO_READONLY)
     #if defined(CFG_EXAMPLE_VIDEO_DISABLE_MJPEG)
     tud_video_n_frame_xfer(0, 0, (void*)(uintptr_t)&frame_buffer[(frame_num % (FRAME_WIDTH / 2)) * 4],
                            FRAME_WIDTH * FRAME_HEIGHT * 16/8);
@@ -220,7 +257,9 @@ static void video_send_frame(void) {
   start_ms += interval_ms;
   tx_busy = 1;
 
-#ifdef CFG_EXAMPLE_VIDEO_READONLY
+#if defined(CFG_EXAMPLE_VIDEO_BUFFERLESS)
+  tud_video_n_frame_xfer(0, 0, NULL, FRAME_WIDTH * FRAME_HEIGHT * 16 / 8);
+#elif defined(CFG_EXAMPLE_VIDEO_READONLY)
   #if defined(CFG_EXAMPLE_VIDEO_DISABLE_MJPEG)
   tud_video_n_frame_xfer(0, 0, (void*)(uintptr_t)&frame_buffer[(frame_num % (FRAME_WIDTH / 2)) * 4],
                          FRAME_WIDTH * FRAME_HEIGHT * 16/8);
diff --git a/examples/device/video_capture/src/tusb_config.h b/examples/device/video_capture/src/tusb_config.h
index 390152e16..1aa1a5ce7 100644
--- a/examples/device/video_capture/src/tusb_config.h
+++ b/examples/device/video_capture/src/tusb_config.h
@@ -110,6 +110,7 @@
 
 //#define CFG_EXAMPLE_VIDEO_READONLY
 //#define CFG_EXAMPLE_VIDEO_DISABLE_MJPEG
+//#define CFG_EXAMPLE_VIDEO_BUFFERLESS
 
 #ifdef __cplusplus
  }
diff --git a/examples/device/video_capture_2ch/skip.txt b/examples/device/video_capture_2ch/skip.txt
index 0f6508226..af3b0de04 100644
--- a/examples/device/video_capture_2ch/skip.txt
+++ b/examples/device/video_capture_2ch/skip.txt
@@ -6,7 +6,6 @@ mcu:CH32V103
 mcu:CH32V20X
 mcu:CH32V307
 mcu:STM32L0
-mcu:MCXA15
 family:espressif
 board:curiosity_nano
 board:kuiic
diff --git a/examples/dual/host_info_to_device_cdc/src/main.c b/examples/dual/host_info_to_device_cdc/src/main.c
index 03a1ac3d8..00d059b66 100644
--- a/examples/dual/host_info_to_device_cdc/src/main.c
+++ b/examples/dual/host_info_to_device_cdc/src/main.c
@@ -69,7 +69,7 @@ enum {
 
 static uint32_t blink_interval_ms = BLINK_NOT_MOUNTED;
 
-static bool is_print[CFG_TUH_DEVICE_MAX+1] = { 0 };
+static bool               is_printable[CFG_TUH_DEVICE_MAX + 1] = {0};
 static tusb_desc_device_t descriptor_device[CFG_TUH_DEVICE_MAX+1];
 
 static void print_utf16(uint16_t *temp_buf, size_t buf_len);
@@ -106,6 +106,10 @@ static void usb_device_init(void) {
     .speed = TUSB_SPEED_AUTO
   };
   tusb_init(BOARD_TUD_RHPORT, &dev_init);
+  tud_cdc_configure_t cdc_cfg = TUD_CDC_CONFIGURE_DEFAULT();
+  cdc_cfg.tx_persistent       = true;
+  cdc_cfg.tx_overwritabe_if_not_connected = false;
+  tud_cdc_configure(&cdc_cfg);
   board_init_after_tusb();
 }
 
@@ -206,17 +210,23 @@ void tud_resume_cb(void) {
 }
 
 void cdc_task(void) {
+  static uint32_t connected_ms = 0;
+
   if (!tud_cdc_connected()) {
-    // delay a bit otherwise we can outpace host's terminal. Linux will set LineState (DTR) then Line Coding.
-    // If we send data before Linux's terminal set Line Coding, it can be ignored --> missing data with hardware test loop
-    tusb_time_delay_ms_api(20);
+    connected_ms = board_millis();
     return;
   }
 
+  // delay a bit otherwise we can outpace host's terminal. Linux will set LineState (DTR) then Line Coding.
+  // If we send data before Linux's terminal set Line Coding, it can be ignored --> missing data with hardware test loop
+  if (board_millis() - connected_ms < 100) {
+    return; // wait for stable connection
+  }
+
   for (uint8_t daddr = 1; daddr <= CFG_TUH_DEVICE_MAX; daddr++) {
     if (tuh_mounted(daddr)) {
-      if (is_print[daddr]) {
-        is_print[daddr] = false;
+      if (is_printable[daddr]) {
+        is_printable[daddr] = false;
         print_device_info(daddr, &descriptor_device[daddr]);
         tud_cdc_write_flush();
       }
@@ -283,13 +293,13 @@ void tuh_enum_descriptor_device_cb(uint8_t daddr, tusb_desc_device_t const* desc
 void tuh_mount_cb(uint8_t daddr) {
   cdc_printf("mounted device %u\r\n", daddr);
   tud_cdc_write_flush();
-  is_print[daddr] = true;
+  is_printable[daddr] = true;
 }
 
 void tuh_umount_cb(uint8_t daddr) {
   cdc_printf("unmounted device %u\r\n", daddr);
   tud_cdc_write_flush();
-  is_print[daddr] = false;
+  is_printable[daddr] = false;
 }
 
 //--------------------------------------------------------------------+
diff --git a/examples/dual/host_info_to_device_cdc/src/tusb_config.h b/examples/dual/host_info_to_device_cdc/src/tusb_config.h
index bb47fbf4a..601c27dae 100644
--- a/examples/dual/host_info_to_device_cdc/src/tusb_config.h
+++ b/examples/dual/host_info_to_device_cdc/src/tusb_config.h
@@ -112,7 +112,7 @@
 
 // CDC FIFO size of TX and RX
 #define CFG_TUD_CDC_RX_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)
-#define CFG_TUD_CDC_TX_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)
+#define CFG_TUD_CDC_TX_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 256)
 
 // CDC Endpoint transfer buffer size, more is faster
 #define CFG_TUD_CDC_EP_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)
diff --git a/examples/host/device_info/src/main.c b/examples/host/device_info/src/main.c
index f71702efc..5b914a2ee 100644
--- a/examples/host/device_info/src/main.c
+++ b/examples/host/device_info/src/main.c
@@ -99,6 +99,7 @@ int main(void) {
 #if CFG_TUSB_OS == OPT_OS_FREERTOS
   init_freertos_task();
 #else
+  board_delay(100); // wait for uart to be ready
   init_tinyusb();
   while (1) {
     tuh_task();     // tinyusb host task
@@ -289,6 +290,7 @@ void app_main(void) {
 
 void usb_host_task(void *param) {
   (void) param;
+  board_delay(100); // wait for uart to be ready
   init_tinyusb();
   while (1) {
     tuh_task();