fix(hid): Eliminate data race in USB pathway causing dropped keys

Closes zmkfirmware#2253

app/src/usb_hid.c

@@ -4,6 +4,8 @@
  * SPDX-License-Identifier: MIT
  */
 
+#include <zephyr/sys/util.h>
+
 #include <zephyr/device.h>
 #include <zephyr/init.h>
 
@@ -18,11 +20,28 @@
 #endif // IS_ENABLED(CONFIG_ZMK_HID_INDICATORS)
 #include <zmk/event_manager.h>
 
+#if IS_ENABLED(CONFIG_ZMK_USB_BOOT)
+#define HID_BOOT_REPORT_SIZE sizeof(zmk_hid_boot_report_t)
+#else
+#define HID_BOOT_REPORT_SIZE 0
+#endif
+
+#if IS_ENABLED(CONFIG_ZMK_MOUSE)
+#define HID_MOUSE_REPORT_SIZE sizeof(struct zmk_hid_mouse_report)
+#else
+#define HID_MOUSE_REPORT_SIZE 0
+#endif
+
+#define HID_EP_WRITE_BUF_SIZE                                                                      \
+    MAX(MAX(HID_BOOT_REPORT_SIZE, sizeof(struct zmk_hid_keyboard_report)),                         \
+        MAX(sizeof(struct zmk_hid_consumer_report), HID_MOUSE_REPORT_SIZE))
+
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
 static const struct device *hid_dev;
 
 static K_SEM_DEFINE(hid_sem, 1, 1);
+static uint8_t hid_ep_write_buf[HID_EP_WRITE_BUF_SIZE];
 
 static void in_ready_cb(const struct device *dev) { k_sem_give(&hid_sem); }
 
@@ -137,7 +156,8 @@ static int zmk_usb_hid_send_report(const uint8_t *report, size_t len) {
         return -ENODEV;
     default:
         k_sem_take(&hid_sem, K_MSEC(30));
-        int err = hid_int_ep_write(hid_dev, report, len, NULL);
+        memcpy(hid_ep_write_buf, report, len);
+        int err = hid_int_ep_write(hid_dev, hid_ep_write_buf, len, NULL);
 
         if (err) {
             k_sem_give(&hid_sem);