1 files changed, 31 insertions, 12 deletions

diff --git a/examples/host/bare_api/src/main.c b/examples/host/bare_api/src/main.c
index 544f38102..679ce6f43 100644
--- a/examples/host/bare_api/src/main.c
+++ b/examples/host/bare_api/src/main.c
@@ -48,14 +48,19 @@ CFG_TUH_MEM_SECTION uint16_t temp_buf[128]; // temp buffer for string descriptor
 // MACRO CONSTANT TYPEDEF PROTYPES
 //--------------------------------------------------------------------+
 void led_blinking_task(void);
+void print_devinfo_task(void);
 
 static void print_utf16(uint16_t *temp_buf, size_t buf_len);
-void print_device_descriptor(tuh_xfer_t* xfer);
+static void print_one_device(uint8_t daddr);
 void parse_config_descriptor(uint8_t dev_addr, tusb_desc_configuration_t const* desc_cfg);
 
 uint8_t* get_hid_buf(uint8_t daddr);
 void free_hid_buf(uint8_t daddr);
 
+// One flag per possible device address — set in tuh_mount_cb (host task) and
+// cleared by print_devinfo_task (main loop) once the descriptors are printed.
+static volatile bool need_devinfo[CFG_TUH_DEVICE_MAX + 1];
+
 /*------------- MAIN -------------*/
 int main(void) {
   board_init();
@@ -74,38 +79,53 @@ int main(void) {
   while (1) {
     // tinyusb host task
     tuh_task();
+    print_devinfo_task();
     led_blinking_task();
   }
 }
 
 /*------------- TinyUSB Callbacks -------------*/
 
-// Invoked when device is mounted (configured)
+// Invoked when device is mounted (configured). Runs in the host task — keep
+// it minimal. The descriptor fetching/printing happens in print_devinfo_task()
+// below where the sync helpers are safe (different context).
 void tuh_mount_cb(uint8_t daddr) {
   printf("Device attached, address = %d\r\n", daddr);
-
-  // Get Device Descriptor
-  // TODO: invoking control transfer now has issue with mounting hub with multiple devices attached, fix later
-  tuh_descriptor_get_device(daddr, &desc_device, 18, print_device_descriptor, 0);
+  if (daddr < TU_ARRAY_SIZE(need_devinfo)) {
+    need_devinfo[daddr] = true;
+  }
 }
 
 /// Invoked when device is unmounted (bus reset/unplugged)
 void tuh_umount_cb(uint8_t daddr) {
   printf("Device removed, address = %d\r\n", daddr);
+  if (daddr < TU_ARRAY_SIZE(need_devinfo)) {
+    need_devinfo[daddr] = false;
+  }
   free_hid_buf(daddr);
 }
 
 //--------------------------------------------------------------------+
-// Device Descriptor
+// Print device info task — serialises descriptor fetching across all
+// mounted devices via sync helpers. Sync calls are safe here because this
+// runs in the main loop (outside any host-stack callback context).
 //--------------------------------------------------------------------+
-void print_device_descriptor(tuh_xfer_t *xfer) {
-  if (XFER_RESULT_SUCCESS != xfer->result) {
+void print_devinfo_task(void) {
+  for (uint8_t daddr = 1; daddr < TU_ARRAY_SIZE(need_devinfo); daddr++) {
+    if (need_devinfo[daddr]) {
+      need_devinfo[daddr] = false;
+      print_one_device(daddr);
+    }
+  }
+}
+
+static void print_one_device(uint8_t daddr) {
+  // Get Device Descriptor
+  if (XFER_RESULT_SUCCESS != tuh_descriptor_get_device_sync(daddr, &desc_device, 18)) {
     printf("Failed to get device descriptor\r\n");
     return;
   }
 
-  uint8_t const daddr = xfer->daddr;
-
   printf("Device %u: ID %04x:%04x\r\n", daddr, desc_device.idVendor, desc_device.idProduct);
   printf("Device Descriptor:\r\n");
   printf("  bLength             %u\r\n"     , desc_device.bLength);
@@ -119,7 +139,6 @@ void print_device_descriptor(tuh_xfer_t *xfer) {
   printf("  idProduct           0x%04x\r\n" , desc_device.idProduct);
   printf("  bcdDevice           %04x\r\n"   , desc_device.bcdDevice);
 
-  // Get String descriptor using Sync API
   printf("  iManufacturer       %u     ", desc_device.iManufacturer);
   if (XFER_RESULT_SUCCESS == tuh_descriptor_get_manufacturer_string_sync(daddr, LANGUAGE_ID, temp_buf, sizeof(temp_buf))) {
     print_utf16(temp_buf, TU_ARRAY_SIZE(temp_buf));