esp-idf/components/usb/hub.c

/*
 * SPDX-FileCopyrightText: 2015-2022 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include "sdkconfig.h"
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/portmacro.h"
#include "esp_err.h"
#include "esp_heap_caps.h"
#include "esp_log.h"
#include "usb_private.h"
#include "hcd.h"
#include "hub.h"
#include "usb/usb_helpers.h"

/*
Implementation of the HUB driver that only supports the Root Hub with a single port. Therefore, we currently don't
implement the bare minimum to control the root HCD port.
*/

#define HUB_ROOT_PORT_NUM                           1   //HCD only supports one port
#ifdef CONFIG_USB_HOST_HW_BUFFER_BIAS_IN
#define HUB_ROOT_HCD_PORT_FIFO_BIAS                 HCD_PORT_FIFO_BIAS_RX
#elif CONFIG_USB_HOST_HW_BUFFER_BIAS_PERIODIC_OUT
#define HUB_ROOT_HCD_PORT_FIFO_BIAS                 HCD_PORT_FIFO_BIAS_PTX
#else   //CONFIG_USB_HOST_HW_BUFFER_BIAS_BALANCED
#define HUB_ROOT_HCD_PORT_FIFO_BIAS                 HCD_PORT_FIFO_BIAS_BALANCED
#endif

#define ENUM_CTRL_TRANSFER_MAX_DATA_LEN             CONFIG_USB_HOST_CONTROL_TRANSFER_MAX_SIZE
#define ENUM_DEV_ADDR                               1       //Device address used in enumeration
#define ENUM_CONFIG_INDEX                           0       //Index of the first configuration of the device
#define ENUM_SHORT_DESC_REQ_LEN                     8       //Number of bytes to request when getting a short descriptor (just enough to get bMaxPacketSize0 or wTotalLength)
#define ENUM_WORST_CASE_MPS_LS                      8       //The worst case MPS of EP0 for a LS device
#define ENUM_WORST_CASE_MPS_FS                      64      //The worst case MPS of EP0 for a FS device
#define ENUM_LOW_SPEED_MPS                          8       //Worst case MPS for the default endpoint of a low-speed device
#define ENUM_FULL_SPEED_MPS                         64      //Worst case MPS for the default endpoint of a full-speed device
#define ENUM_LANGID                                 0x409   //Current enumeration only supports English (United States) string descriptors

//Hub driver action flags. LISTED IN THE ORDER THEY SHOULD BE HANDLED IN within hub_process(). Some actions are mutually exclusive
#define HUB_DRIVER_FLAG_ACTION_ROOT_EVENT           0x01
#define HUB_DRIVER_FLAG_ACTION_PORT_DISABLE         0x02
#define HUB_DRIVER_FLAG_ACTION_PORT_RECOVER         0x04
#define HUB_DRIVER_FLAG_ACTION_ENUM_EVENT           0x08

/**
 * @brief Hub driver states
 *
 * These states represent a Hub driver that only has a single port (the root port)
 */
typedef enum {
    HUB_DRIVER_STATE_INSTALLED,             /**< Hub driver is installed. Root port is not powered */
    HUB_DRIVER_STATE_ROOT_POWERED,          /**< Root port is powered, is not connected */
    HUB_DRIVER_STATE_ROOT_ENUM,             /**< A device has connected to the root port and is undergoing enumeration */
    HUB_DRIVER_STATE_ROOT_ENUM_FAILED,      /**< Enumeration of a connect device has failed. Waiting for that device to disconnect */
    HUB_DRIVER_STATE_ROOT_ACTIVE,           /**< The connected device is enumerated */
    HUB_DRIVER_STATE_ROOT_RECOVERY,         /**< Root port encountered an error and needs to be recovered */
} hub_driver_state_t;

/**
 * @brief Stages of device enumeration listed in their order of execution
 *
 * - These stages MUST BE LISTED IN THE ORDER OF THEIR EXECUTION as the enumeration will simply increment the current stage
 * - If an error occurs at any stage, ENUM_STAGE_CLEANUP_FAILED acts as a common exit stage on failure
 * - Must start with 0 as enum is also used as an index
 * - The short descriptor stages are used to fetch the start particular descriptors that don't have a fixed length in order to determine the full descriptors length
 */
typedef enum {
    ENUM_STAGE_NONE = 0,                    /**< There is no device awaiting enumeration. Start requires device connection and first reset. */
    ENUM_STAGE_START,                       /**< A device has connected and has already been reset once. Allocate a device object in USBH */
    //Basic device enumeration
    ENUM_STAGE_GET_SHORT_DEV_DESC,          /**< Getting short dev desc (wLength is ENUM_SHORT_DESC_REQ_LEN) */
    ENUM_STAGE_CHECK_SHORT_DEV_DESC,        /**< Save bMaxPacketSize0 from the short dev desc. Update the MPS of the enum pipe */
    ENUM_STAGE_SECOND_RESET,                /**< Reset the device again (Workaround for old USB devices that get confused by the previous short dev desc request). */
    ENUM_STAGE_SET_ADDR,                    /**< Send SET_ADDRESS request */
    ENUM_STAGE_CHECK_ADDR,                  /**< Update the enum pipe's target address */
    ENUM_STAGE_GET_FULL_DEV_DESC,           /**< Get the full dev desc */
    ENUM_STAGE_CHECK_FULL_DEV_DESC,         /**< Check the full dev desc, fill it into the device object in USBH. Save the string descriptor indexes*/
    ENUM_STAGE_GET_SHORT_CONFIG_DESC,       /**< Getting a short config desc (wLength is ENUM_SHORT_DESC_REQ_LEN) */
    ENUM_STAGE_CHECK_SHORT_CONFIG_DESC,     /**< Save wTotalLength of the short config desc */
    ENUM_STAGE_GET_FULL_CONFIG_DESC,        /**< Get the full config desc (wLength is the saved wTotalLength) */
    ENUM_STAGE_CHECK_FULL_CONFIG_DESC,      /**< Check the full config desc, fill it into the device object in USBH */
    ENUM_STAGE_SET_CONFIG,                  /**< Send SET_CONFIGURATION request */
    ENUM_STAGE_CHECK_CONFIG,                /**< Check that SET_CONFIGURATION request was successful */
    //Get string descriptors
    ENUM_STAGE_GET_SHORT_LANGID_TABLE,      /**< Get the header of the LANGID table string descriptor */
    ENUM_STAGE_CHECK_SHORT_LANGID_TABLE,    /**< Save the bLength of the LANGID table string descriptor */
    ENUM_STAGE_GET_FULL_LANGID_TABLE,       /**< Get the full LANGID table string descriptor */
    ENUM_STAGE_CHECK_FULL_LANGID_TABLE,     /**< Check whether ENUM_LANGID is in the LANGID table */
    ENUM_STAGE_GET_SHORT_MANU_STR_DESC,     /**< Get the header of the iManufacturer string descriptor */
    ENUM_STAGE_CHECK_SHORT_MANU_STR_DESC,   /**< Save the bLength of the iManufacturer string descriptor */
    ENUM_STAGE_GET_FULL_MANU_STR_DESC,      /**< Get the full iManufacturer string descriptor */
    ENUM_STAGE_CHECK_FULL_MANU_STR_DESC,    /**< Check and fill the full iManufacturer string descriptor */
    ENUM_STAGE_GET_SHORT_PROD_STR_DESC,     /**< Get the header of the string descriptor at index iProduct */
    ENUM_STAGE_CHECK_SHORT_PROD_STR_DESC,   /**< Save the bLength of the iProduct string descriptor */
    ENUM_STAGE_GET_FULL_PROD_STR_DESC,      /**< Get the full iProduct string descriptor */
    ENUM_STAGE_CHECK_FULL_PROD_STR_DESC,    /**< Check and fill the full iProduct string descriptor */
    ENUM_STAGE_GET_SHORT_SER_STR_DESC,      /**< Get the header of the string descriptor at index iSerialNumber */
    ENUM_STAGE_CHECK_SHORT_SER_STR_DESC,    /**< Save the bLength of the iSerialNumber string descriptor */
    ENUM_STAGE_GET_FULL_SER_STR_DESC,       /**< Get the full iSerialNumber string descriptor */
    ENUM_STAGE_CHECK_FULL_SER_STR_DESC,     /**< Check and fill the full iSerialNumber string descriptor */
    //Cleanup
    ENUM_STAGE_CLEANUP,                     /**< Clean up after successful enumeration. Adds enumerated device to USBH */
    ENUM_STAGE_CLEANUP_FAILED,              /**< Cleanup failed enumeration. Free device resources */
} enum_stage_t;

const char *const enum_stage_strings[] = {
    "NONE",
    "START",
    "GET_SHORT_DEV_DESC",
    "CHECK_SHORT_DEV_DESC",
    "SECOND_RESET",
    "SET_ADDR",
    "CHECK_ADDR",
    "GET_FULL_DEV_DESC",
    "CHECK_FULL_DEV_DESC",
    "GET_SHORT_CONFIG_DESC",
    "CHECK_SHORT_CONFIG_DESC",
    "GET_FULL_CONFIG_DESC",
    "CHECK_FULL_CONFIG_DESC",
    "SET_CONFIG",
    "CHECK_CONFIG",
    "GET_SHORT_LANGID_TABLE",
    "CHECK_SHORT_LANGID_TABLE",
    "GET_FULL_LANGID_TABLE",
    "CHECK_FULL_LANGID_TABLE",
    "GET_SHORT_MANU_STR_DESC",
    "CHECK_SHORT_MANU_STR_DESC",
    "GET_FULL_MANU_STR_DESC",
    "CHECK_FULL_MANU_STR_DESC",
    "GET_SHORT_PROD_STR_DESC",
    "CHECK_SHORT_PROD_STR_DESC",
    "GET_FULL_PROD_STR_DESC",
    "CHECK_FULL_PROD_STR_DESC",
    "GET_SHORT_SER_STR_DESC",
    "CHECK_SHORT_SER_STR_DESC",
    "GET_FULL_SER_STR_DESC",
    "CHECK_FULL_SER_STR_DESC",
    "CLEANUP",
    "CLEANUP_FAILED",
};

typedef struct {
    //Constant
    urb_t *urb;                     /**< URB used for enumeration control transfers. Max data length of ENUM_CTRL_TRANSFER_MAX_DATA_LEN */
    //Initialized at start of a particular enumeration
    usb_device_handle_t dev_hdl;    /**< Handle of device being enumerated */
    hcd_pipe_handle_t pipe;         /**< Default pipe handle of the device being enumerated */
    //Updated during enumeration
    enum_stage_t stage;             /**< Current enumeration stage */
    int expect_num_bytes;           /**< Expected number of bytes for IN transfers stages. Set to 0 for OUT transfer */
    uint8_t bMaxPacketSize0;        /**< Max packet size of the device's EP0. Read from bMaxPacketSize0 field of device descriptor */
    uint8_t wTotalLength;           /**< Total length of device's configuration descriptor. Read from wTotalLength field of config descriptor */
    uint8_t iManufacturer;          /**< Index of the Manufacturer string descriptor */
    uint8_t iProduct;               /**< Index of the Product string descriptor */
    uint8_t iSerialNumber;          /**< Index of the Serial Number string descriptor */
    uint8_t str_desc_bLength;       /**< Saved bLength from getting a short string descriptor */
} enum_ctrl_t;

typedef struct {
    //Dynamic members require a critical section
    struct {
        union {
            struct {
                uint32_t actions: 8;
                uint32_t reserved24: 24;
            };
            uint32_t val;
        } flags;
        hub_driver_state_t driver_state;
    } dynamic;
    //Single thread members don't require a critical section so long as they are never accessed from multiple threads
    struct {
        usb_device_handle_t root_dev_hdl;   //Indicates if an enumerated device is connected to the root port
        enum_ctrl_t enum_ctrl;
    } single_thread;
    //Constant members do no change after installation thus do not require a critical section
    struct {
        hcd_port_handle_t root_port_hdl;
        usb_notif_cb_t notif_cb;
        void *notif_cb_arg;
    } constant;
} hub_driver_t;

static hub_driver_t *p_hub_driver_obj = NULL;
static portMUX_TYPE hub_driver_lock = portMUX_INITIALIZER_UNLOCKED;

const char *HUB_DRIVER_TAG = "HUB";

#define HUB_DRIVER_ENTER_CRITICAL_ISR()                 portENTER_CRITICAL_ISR(&hub_driver_lock)
#define HUB_DRIVER_EXIT_CRITICAL_ISR()                  portEXIT_CRITICAL_ISR(&hub_driver_lock)
#define HUB_DRIVER_ENTER_CRITICAL()                     portENTER_CRITICAL(&hub_driver_lock)
#define HUB_DRIVER_EXIT_CRITICAL()                      portEXIT_CRITICAL(&hub_driver_lock)
#define HUB_DRIVER_ENTER_CRITICAL_SAFE()                portENTER_CRITICAL_SAFE(&hub_driver_lock)
#define HUB_DRIVER_EXIT_CRITICAL_SAFE()                 portEXIT_CRITICAL_SAFE(&hub_driver_lock)

#define HUB_DRIVER_CHECK(cond, ret_val) ({              \
            if (!(cond)) {                              \
                return (ret_val);                       \
            }                                           \
})
#define HUB_DRIVER_CHECK_FROM_CRIT(cond, ret_val) ({    \
            if (!(cond)) {                              \
                HUB_DRIVER_EXIT_CRITICAL();             \
                return ret_val;                         \
            }                                           \
})

// ------------------------------------------------- Forward Declare ---------------------------------------------------

/**
 * @brief HCD port callback for the root port
 *
 * - This callback is called from the context of the HCD, so any event handling should be deferred to hub_process()
 * - Under the current HCD implementation, this callback should only be ever be called in an ISR
 * - This callback needs to call the notification to ensure hub_process() gets a chance to run
 *
 * @param port_hdl HCD port handle
 * @param port_event HCD port event
 * @param user_arg Callback argument
 * @param in_isr Whether callback is in an ISR context
 * @return Whether a yield is required
 */
static bool root_port_callback(hcd_port_handle_t port_hdl, hcd_port_event_t port_event, void *user_arg, bool in_isr);

/**
 * @brief HCD pipe callback for the default pipe of the device under enumeration
 *
 * - This callback is called from the context of the HCD, so any event handling should be deferred to hub_process()
 * - This callback needs to call the notification to ensure hub_process() gets a chance to run
 *
 * @param pipe_hdl HCD pipe handle
 * @param pipe_event Pipe event
 * @param user_arg Callback argument
 * @param in_isr Whether callback is in an ISR context
 * @return Whether a yield is required
 */
static bool enum_dflt_pipe_callback(hcd_pipe_handle_t pipe_hdl, hcd_pipe_event_t pipe_event, void *user_arg, bool in_isr);

/**
 * @brief USBH Hub driver request callback
 *
 * - This callback is called from the context of the USBH, so so any event handling should be deferred to hub_process()
 * - This callback needs to call the notification to ensure hub_process() gets a chance to run
 *
 * @param port_hdl HCD port handle
 * @param hub_req Hub driver request
 * @param arg Callback argument
 */
static void usbh_hub_req_callback(hcd_port_handle_t port_hdl, usbh_hub_req_t hub_req, void *arg);

// ------------------------------------------------- Enum Functions ----------------------------------------------------

static bool enum_stage_start(enum_ctrl_t *enum_ctrl)
{
    //Get the speed of the device, and set the enum MPS to the worst case size for now
    usb_speed_t speed;
    if (hcd_port_get_speed(p_hub_driver_obj->constant.root_port_hdl, &speed) != ESP_OK) {
        return false;
    }
    enum_ctrl->bMaxPacketSize0 = (speed == USB_SPEED_LOW) ? ENUM_WORST_CASE_MPS_LS : ENUM_WORST_CASE_MPS_FS;
    //Try to add the device to USBH
    usb_device_handle_t enum_dev_hdl;
    hcd_pipe_handle_t enum_dflt_pipe_hdl;
    //We use NULL as the parent device to indicate the Root Hub port 1. We currently only support a single device
    if (usbh_hub_add_dev(p_hub_driver_obj->constant.root_port_hdl, speed, &enum_dev_hdl, &enum_dflt_pipe_hdl) != ESP_OK) {
        return false;
    }
    //Set our own default pipe callback
    ESP_ERROR_CHECK(hcd_pipe_update_callback(enum_dflt_pipe_hdl, enum_dflt_pipe_callback, NULL));
    enum_ctrl->dev_hdl = enum_dev_hdl;
    enum_ctrl->pipe = enum_dflt_pipe_hdl;
    return true;
}

static bool enum_stage_second_reset(enum_ctrl_t *enum_ctrl)
{
    ESP_ERROR_CHECK(hcd_pipe_set_persist_reset(enum_ctrl->pipe));  //Persist the default pipe through the reset
    if (hcd_port_command(p_hub_driver_obj->constant.root_port_hdl, HCD_PORT_CMD_RESET) != ESP_OK) {
        ESP_LOGE(HUB_DRIVER_TAG, "Failed to issue second reset");
        return false;
    }
    return true;
}

static uint8_t get_string_desc_index(enum_ctrl_t *enum_ctrl)
{
    uint8_t index;
    switch (enum_ctrl->stage) {
        case ENUM_STAGE_GET_SHORT_LANGID_TABLE:
        case ENUM_STAGE_GET_FULL_LANGID_TABLE:
            index = 0;  //The LANGID table uses an index of 0
            break;
        case ENUM_STAGE_GET_SHORT_MANU_STR_DESC:
        case ENUM_STAGE_GET_FULL_MANU_STR_DESC:
            index = enum_ctrl->iManufacturer;
            break;
        case ENUM_STAGE_GET_SHORT_PROD_STR_DESC:
        case ENUM_STAGE_GET_FULL_PROD_STR_DESC:
            index = enum_ctrl->iProduct;
            break;
        case ENUM_STAGE_GET_SHORT_SER_STR_DESC:
        case ENUM_STAGE_GET_FULL_SER_STR_DESC:
            index = enum_ctrl->iSerialNumber;
            break;
        default:
            //Should not occur
            index = 0;
            abort();
            break;
    }
    return index;
}

static bool enum_stage_transfer(enum_ctrl_t *enum_ctrl)
{
    usb_transfer_t *transfer = &enum_ctrl->urb->transfer;
    switch (enum_ctrl->stage) {
        case ENUM_STAGE_GET_SHORT_DEV_DESC: {
            //Initialize a short device descriptor request
            USB_SETUP_PACKET_INIT_GET_DEVICE_DESC((usb_setup_packet_t *)transfer->data_buffer);
            ((usb_setup_packet_t *)transfer->data_buffer)->wLength = ENUM_SHORT_DESC_REQ_LEN;
            transfer->num_bytes = sizeof(usb_setup_packet_t) + usb_round_up_to_mps(ENUM_SHORT_DESC_REQ_LEN, enum_ctrl->bMaxPacketSize0);
            //IN data stage should return exactly ENUM_SHORT_DESC_REQ_LEN bytes
            enum_ctrl->expect_num_bytes = sizeof(usb_setup_packet_t) + ENUM_SHORT_DESC_REQ_LEN;
            break;
        }
        case ENUM_STAGE_SET_ADDR: {
            USB_SETUP_PACKET_INIT_SET_ADDR((usb_setup_packet_t *)transfer->data_buffer, ENUM_DEV_ADDR);
            transfer->num_bytes = sizeof(usb_setup_packet_t);   //No data stage
            enum_ctrl->expect_num_bytes = 0;    //OUT transfer. No need to check number of bytes returned
            break;
        }
        case ENUM_STAGE_GET_FULL_DEV_DESC: {
            USB_SETUP_PACKET_INIT_GET_DEVICE_DESC((usb_setup_packet_t *)transfer->data_buffer);
            transfer->num_bytes = sizeof(usb_setup_packet_t) + usb_round_up_to_mps(sizeof(usb_device_desc_t), enum_ctrl->bMaxPacketSize0);
            //IN data stage should return exactly sizeof(usb_device_desc_t) bytes
            enum_ctrl->expect_num_bytes = sizeof(usb_setup_packet_t) + sizeof(usb_device_desc_t);
            break;
        }
        case ENUM_STAGE_GET_SHORT_CONFIG_DESC: {
            //Get a short config descriptor at index 0
            USB_SETUP_PACKET_INIT_GET_CONFIG_DESC((usb_setup_packet_t *)transfer->data_buffer, ENUM_CONFIG_INDEX, ENUM_SHORT_DESC_REQ_LEN);
            transfer->num_bytes = sizeof(usb_setup_packet_t) + usb_round_up_to_mps(ENUM_SHORT_DESC_REQ_LEN, enum_ctrl->bMaxPacketSize0);
            //IN data stage should return exactly ENUM_SHORT_DESC_REQ_LEN bytes
            enum_ctrl->expect_num_bytes = sizeof(usb_setup_packet_t) + ENUM_SHORT_DESC_REQ_LEN;
            break;
        }
        case ENUM_STAGE_GET_FULL_CONFIG_DESC: {
            //Get the full configuration descriptor at index 0, requesting its exact length.
            USB_SETUP_PACKET_INIT_GET_CONFIG_DESC((usb_setup_packet_t *)transfer->data_buffer, ENUM_CONFIG_INDEX, enum_ctrl->wTotalLength);
            transfer->num_bytes = sizeof(usb_setup_packet_t) + usb_round_up_to_mps(enum_ctrl->wTotalLength, enum_ctrl->bMaxPacketSize0);
            //IN data stage should return exactly wTotalLength bytes
            enum_ctrl->expect_num_bytes = sizeof(usb_setup_packet_t) + enum_ctrl->wTotalLength;
            break;
        }
        case ENUM_STAGE_SET_CONFIG: {
            USB_SETUP_PACKET_INIT_SET_CONFIG((usb_setup_packet_t *)transfer->data_buffer, ENUM_CONFIG_INDEX + 1);
            transfer->num_bytes = sizeof(usb_setup_packet_t);   //No data stage
            enum_ctrl->expect_num_bytes = 0;    //OUT transfer. No need to check number of bytes returned
            break;
        }
        case ENUM_STAGE_GET_SHORT_LANGID_TABLE:
        case ENUM_STAGE_GET_SHORT_MANU_STR_DESC:
        case ENUM_STAGE_GET_SHORT_PROD_STR_DESC:
        case ENUM_STAGE_GET_SHORT_SER_STR_DESC: {
            uint8_t index = get_string_desc_index(enum_ctrl);
            //Get only the header of the string descriptor
            USB_SETUP_PACKET_INIT_GET_STR_DESC((usb_setup_packet_t *)transfer->data_buffer,
                                               index,
                                               ENUM_LANGID,
                                               sizeof(usb_str_desc_t));
            transfer->num_bytes = sizeof(usb_setup_packet_t) + usb_round_up_to_mps(sizeof(usb_str_desc_t), enum_ctrl->bMaxPacketSize0);
            //IN data stage should return exactly sizeof(usb_str_desc_t) bytes
            enum_ctrl->expect_num_bytes = sizeof(usb_setup_packet_t) + sizeof(usb_str_desc_t);
            break;
        }
        case ENUM_STAGE_GET_FULL_LANGID_TABLE:
        case ENUM_STAGE_GET_FULL_MANU_STR_DESC:
        case ENUM_STAGE_GET_FULL_PROD_STR_DESC:
        case ENUM_STAGE_GET_FULL_SER_STR_DESC: {
            uint8_t index = get_string_desc_index(enum_ctrl);
            //Get the full string descriptor at a particular index, requesting the descriptors exact length
            USB_SETUP_PACKET_INIT_GET_STR_DESC((usb_setup_packet_t *)transfer->data_buffer,
                                               index,
                                               ENUM_LANGID,
                                               enum_ctrl->str_desc_bLength);
            transfer->num_bytes = sizeof(usb_setup_packet_t) + usb_round_up_to_mps(enum_ctrl->str_desc_bLength, enum_ctrl->bMaxPacketSize0);
            //IN data stage should return exactly str_desc_bLength bytes
            enum_ctrl->expect_num_bytes = sizeof(usb_setup_packet_t) + enum_ctrl->str_desc_bLength;
            break;
        }
        default:    //Should never occur
            abort();
            break;
    }
    if (hcd_urb_enqueue(enum_ctrl->pipe, enum_ctrl->urb) != ESP_OK) {
        ESP_LOGE(HUB_DRIVER_TAG, "Failed to submit: %s", enum_stage_strings[enum_ctrl->stage]);
        return false;
    }
    return true;
}

static bool enum_stage_transfer_check(enum_ctrl_t *enum_ctrl)
{
    //Dequeue the URB
    urb_t *dequeued_enum_urb = hcd_urb_dequeue(enum_ctrl->pipe);
    assert(dequeued_enum_urb == enum_ctrl->urb);

    //Check transfer status
    usb_transfer_t *transfer = &dequeued_enum_urb->transfer;
    if (transfer->status != USB_TRANSFER_STATUS_COMPLETED) {
        ESP_LOGE(HUB_DRIVER_TAG, "Bad transfer status: %s", enum_stage_strings[enum_ctrl->stage]);
        return false;
    }
    //Check IN transfer returned the expected correct number of bytes
    if (enum_ctrl->expect_num_bytes != 0 && enum_ctrl->expect_num_bytes != transfer->actual_num_bytes) {
        ESP_LOGE(HUB_DRIVER_TAG, "Incorrect number of bytes returned: %s", enum_stage_strings[enum_ctrl->stage]);
        return false;
    }

    //Stage specific checks and updates
    bool ret;
    switch (enum_ctrl->stage) {
        case ENUM_STAGE_CHECK_SHORT_DEV_DESC: {
            const usb_device_desc_t *device_desc = (usb_device_desc_t *)(transfer->data_buffer + sizeof(usb_setup_packet_t));
            //Check if the returned descriptor is corrupted
            if (device_desc->bDescriptorType != USB_B_DESCRIPTOR_TYPE_DEVICE) {
                ESP_LOGE(HUB_DRIVER_TAG, "Short dev desc corrupt");
                ret = false;
                break;
            }
            //Update and save the MPS of the default pipe
            if (hcd_pipe_update_mps(enum_ctrl->pipe, device_desc->bMaxPacketSize0) != ESP_OK) {
                ESP_LOGE(HUB_DRIVER_TAG, "Failed to update MPS");
                ret = false;
                break;
            }
            //Save the actual MPS of EP0
            enum_ctrl->bMaxPacketSize0 = device_desc->bMaxPacketSize0;
            ret = true;
            break;
        }
        case ENUM_STAGE_CHECK_ADDR: {
            //Update the pipe and device's address, and fill the address into the device object
            ESP_ERROR_CHECK(hcd_pipe_update_dev_addr(enum_ctrl->pipe, ENUM_DEV_ADDR));
            ESP_ERROR_CHECK(usbh_hub_enum_fill_dev_addr(enum_ctrl->dev_hdl, ENUM_DEV_ADDR));
            ret = true;
            break;
        }
        case ENUM_STAGE_CHECK_FULL_DEV_DESC: {
            //Fill device descriptor into the device object
            const usb_device_desc_t *device_desc = (const usb_device_desc_t *)(transfer->data_buffer + sizeof(usb_setup_packet_t));
            ESP_ERROR_CHECK(usbh_hub_enum_fill_dev_desc(enum_ctrl->dev_hdl, device_desc));
            enum_ctrl->iManufacturer = device_desc->iManufacturer;
            enum_ctrl->iProduct = device_desc->iProduct;
            enum_ctrl->iSerialNumber = device_desc->iSerialNumber;
            ret = true;
            break;
        }
        case ENUM_STAGE_CHECK_SHORT_CONFIG_DESC: {
            const usb_config_desc_t *config_desc = (usb_config_desc_t *)(transfer->data_buffer + sizeof(usb_setup_packet_t));
            //Check if the returned descriptor is corrupted
            if (config_desc->bDescriptorType != USB_B_DESCRIPTOR_TYPE_CONFIGURATION) {
                ESP_LOGE(HUB_DRIVER_TAG, "Short config desc corrupt");
                ret = false;
                break;
            }
#if (ENUM_CTRL_TRANSFER_MAX_DATA_LEN < UINT16_MAX)  //Suppress -Wtype-limits warning due to uint16_t wTotalLength
            //Check if the descriptor is too long to be supported
            if (config_desc->wTotalLength > ENUM_CTRL_TRANSFER_MAX_DATA_LEN) {
                ESP_LOGE(HUB_DRIVER_TAG, "Configuration descriptor larger than control transfer max length");
                ret = false;
                break;
            }
#endif
            //Save the configuration descriptors full length
            enum_ctrl->wTotalLength = config_desc->wTotalLength;
            ret = true;
            break;
        }
        case ENUM_STAGE_CHECK_FULL_CONFIG_DESC: {
            //Fill configuration descriptor into the device object
            const usb_config_desc_t *config_desc = (usb_config_desc_t *)(transfer->data_buffer + sizeof(usb_setup_packet_t));
            ESP_ERROR_CHECK(usbh_hub_enum_fill_config_desc(enum_ctrl->dev_hdl, config_desc));
            ret = true;
            break;
        }
        case ENUM_STAGE_CHECK_CONFIG: {
            ret = true;
            //Nothing to do
            break;
        }
        case ENUM_STAGE_CHECK_SHORT_LANGID_TABLE:
        case ENUM_STAGE_CHECK_SHORT_MANU_STR_DESC:
        case ENUM_STAGE_CHECK_SHORT_PROD_STR_DESC:
        case ENUM_STAGE_CHECK_SHORT_SER_STR_DESC: {
            const usb_str_desc_t *str_desc = (usb_str_desc_t *)(transfer->data_buffer + sizeof(usb_setup_packet_t));
            //Check if the returned descriptor is supported or corrupted
            if (str_desc->bDescriptorType == 0) {
                ESP_LOGW(HUB_DRIVER_TAG, "String desc not supported");
                ret = false;
                break;
            } else if (str_desc->bDescriptorType != USB_B_DESCRIPTOR_TYPE_STRING) {
                ESP_LOGE(HUB_DRIVER_TAG, "Full string desc corrupt");
                ret = false;
                break;
            }
#if (ENUM_CTRL_TRANSFER_MAX_DATA_LEN < UINT8_MAX)   //Suppress -Wtype-limits warning due to uint8_t bLength
            //Check if the descriptor is too long to be supported
            if (str_desc->bLength > (uint32_t)ENUM_CTRL_TRANSFER_MAX_DATA_LEN) {
                ESP_LOGE(HUB_DRIVER_TAG, "String descriptor larger than control transfer max length");
                ret = false;
                break;
            }
#endif
            //Save the descriptors full length
            enum_ctrl->str_desc_bLength = str_desc->bLength;
            ret = true;
            break;
        }
        case ENUM_STAGE_CHECK_FULL_LANGID_TABLE:
        case ENUM_STAGE_CHECK_FULL_MANU_STR_DESC:
        case ENUM_STAGE_CHECK_FULL_PROD_STR_DESC:
        case ENUM_STAGE_CHECK_FULL_SER_STR_DESC: {
            const usb_str_desc_t *str_desc = (usb_str_desc_t *)(transfer->data_buffer + sizeof(usb_setup_packet_t));
            //Check if the returned descriptor is supported or corrupted
            if (str_desc->bDescriptorType == 0) {
                ESP_LOGW(HUB_DRIVER_TAG, "String desc not supported");
                ret = false;
                break;
            } else if (str_desc->bDescriptorType != USB_B_DESCRIPTOR_TYPE_STRING) {
                ESP_LOGE(HUB_DRIVER_TAG, "Full string desc corrupt");
                ret = false;
                break;
            }
            if (enum_ctrl->stage == ENUM_STAGE_CHECK_FULL_LANGID_TABLE) {
                //Scan the LANGID table for our target LANGID
                bool target_langid_found = false;
                int langid_table_num_entries = (str_desc->bLength - sizeof(usb_str_desc_t))/2;    //Each LANGID is 2 bytes
                for (int i = 0; i < langid_table_num_entries; i++) {  //Each LANGID is 2 bytes
                    if (str_desc->wData[i] == ENUM_LANGID) {
                        target_langid_found = true;
                        break;
                    }
                }
                if (!target_langid_found) {
                    ESP_LOGE(HUB_DRIVER_TAG, "LANGID 0x%x not found", ENUM_LANGID);
                }
                ret = target_langid_found;
                break;
            } else {
                //Fill the string descriptor into the device object
                int select;
                if (enum_ctrl->stage == ENUM_STAGE_CHECK_FULL_MANU_STR_DESC) {
                    select = 0;
                } else if (enum_ctrl->stage == ENUM_STAGE_CHECK_FULL_PROD_STR_DESC) {
                    select = 1;
                } else {    //ENUM_STAGE_CHECK_FULL_PROD_STR_DESC
                    select = 2;
                }
                ESP_ERROR_CHECK(usbh_hub_enum_fill_str_desc(enum_ctrl->dev_hdl, str_desc, select));
                ret = true;
                break;
            }
        }
        default:    //Should never occur
            ret = false;
            abort();
            break;
    }
    return ret;
}

static void enum_stage_cleanup(enum_ctrl_t *enum_ctrl)
{
    //We currently only support a single device connected to the root port. Move the device handle from enum to root
    HUB_DRIVER_ENTER_CRITICAL();
    p_hub_driver_obj->dynamic.driver_state = HUB_DRIVER_STATE_ROOT_ACTIVE;
    HUB_DRIVER_EXIT_CRITICAL();
    p_hub_driver_obj->single_thread.root_dev_hdl = enum_ctrl->dev_hdl;
    usb_device_handle_t dev_hdl = enum_ctrl->dev_hdl;
    //Clear values in enum_ctrl
    enum_ctrl->dev_hdl = NULL;
    enum_ctrl->pipe = NULL;
    //Update device object after enumeration is done
    ESP_ERROR_CHECK(usbh_hub_enum_done(dev_hdl));
}

static void enum_stage_cleanup_failed(enum_ctrl_t *enum_ctrl)
{
    //Enumeration failed. Clear the enum device handle and pipe
    if (enum_ctrl->dev_hdl) {
        //If enumeration failed due to a port event, we need to Halt, flush, and dequeue enum default pipe in case there
        //was an in-flight URB.
        ESP_ERROR_CHECK(hcd_pipe_command(enum_ctrl->pipe, HCD_PIPE_CMD_HALT));
        ESP_ERROR_CHECK(hcd_pipe_command(enum_ctrl->pipe, HCD_PIPE_CMD_FLUSH));
        hcd_urb_dequeue(enum_ctrl->pipe);   //This could return NULL if there
        ESP_ERROR_CHECK(usbh_hub_enum_failed(enum_ctrl->dev_hdl)); //Free the underlying device object first before recovering the port
    }
    //Clear values in enum_ctrl
    enum_ctrl->dev_hdl = NULL;
    enum_ctrl->pipe = NULL;
    HUB_DRIVER_ENTER_CRITICAL();
    //Enum could have failed due to a port error. If so, we need to trigger a port recovery
    if (p_hub_driver_obj->dynamic.driver_state == HUB_DRIVER_STATE_ROOT_RECOVERY) {
        p_hub_driver_obj->dynamic.flags.actions |= HUB_DRIVER_FLAG_ACTION_PORT_RECOVER;
    } else {
        //Otherwise, we move to the enum failed state and wait for the device to disconnect
        p_hub_driver_obj->dynamic.driver_state = HUB_DRIVER_STATE_ROOT_ENUM_FAILED;
    }
    HUB_DRIVER_EXIT_CRITICAL();
}

static void enum_set_next_stage(enum_ctrl_t *enum_ctrl, bool last_stage_pass)
{
    //Set next stage
    if (last_stage_pass) {
        if (enum_ctrl->stage != ENUM_STAGE_NONE &&
            enum_ctrl->stage != ENUM_STAGE_CLEANUP &&
            enum_ctrl->stage != ENUM_STAGE_CLEANUP_FAILED) {
                enum_ctrl->stage++; //Go to next stage
        } else {
                enum_ctrl->stage = ENUM_STAGE_NONE;
        }
    } else {
        switch (enum_ctrl->stage) {
            case ENUM_STAGE_START:
                //Stage failed but clean up not required
                enum_ctrl->stage = ENUM_STAGE_NONE;
                break;
            case ENUM_STAGE_GET_SHORT_LANGID_TABLE:
            case ENUM_STAGE_CHECK_SHORT_LANGID_TABLE:
            case ENUM_STAGE_GET_FULL_LANGID_TABLE:
            case ENUM_STAGE_CHECK_FULL_LANGID_TABLE:
            case ENUM_STAGE_GET_SHORT_MANU_STR_DESC:
            case ENUM_STAGE_CHECK_SHORT_MANU_STR_DESC:
            case ENUM_STAGE_GET_FULL_MANU_STR_DESC:
            case ENUM_STAGE_CHECK_FULL_MANU_STR_DESC:
            case ENUM_STAGE_GET_SHORT_PROD_STR_DESC:
            case ENUM_STAGE_CHECK_SHORT_PROD_STR_DESC:
            case ENUM_STAGE_GET_FULL_PROD_STR_DESC:
            case ENUM_STAGE_CHECK_FULL_PROD_STR_DESC:
            case ENUM_STAGE_GET_SHORT_SER_STR_DESC:
            case ENUM_STAGE_CHECK_SHORT_SER_STR_DESC:
            case ENUM_STAGE_GET_FULL_SER_STR_DESC:
            case ENUM_STAGE_CHECK_FULL_SER_STR_DESC:
                //String descriptor stages are allow to fail. We just don't fetch them and treat enumeration as successful
                enum_ctrl->stage = ENUM_STAGE_CLEANUP;
                break;
            default:
                //Enumeration failed. Go to failure clean up
                enum_ctrl->stage = ENUM_STAGE_CLEANUP_FAILED;
                break;
        }
    }

    //These stages are not waiting for a callback, so we need to re-trigger the enum event
    bool re_trigger;
    switch (enum_ctrl->stage) {
        case ENUM_STAGE_GET_SHORT_DEV_DESC:
        case ENUM_STAGE_SECOND_RESET:
        case ENUM_STAGE_SET_ADDR:
        case ENUM_STAGE_GET_FULL_DEV_DESC:
        case ENUM_STAGE_GET_SHORT_CONFIG_DESC:
        case ENUM_STAGE_GET_FULL_CONFIG_DESC:
        case ENUM_STAGE_SET_CONFIG:
        case ENUM_STAGE_GET_SHORT_LANGID_TABLE:
        case ENUM_STAGE_GET_FULL_LANGID_TABLE:
        case ENUM_STAGE_GET_SHORT_MANU_STR_DESC:
        case ENUM_STAGE_GET_FULL_MANU_STR_DESC:
        case ENUM_STAGE_GET_SHORT_PROD_STR_DESC:
        case ENUM_STAGE_GET_FULL_PROD_STR_DESC:
        case ENUM_STAGE_GET_SHORT_SER_STR_DESC:
        case ENUM_STAGE_GET_FULL_SER_STR_DESC:
        case ENUM_STAGE_CLEANUP:
        case ENUM_STAGE_CLEANUP_FAILED:
            re_trigger = true;
            break;
        default:
            re_trigger = false;
            break;
    }
    if (re_trigger) {
        HUB_DRIVER_ENTER_CRITICAL();
        p_hub_driver_obj->dynamic.flags.actions |= HUB_DRIVER_FLAG_ACTION_ENUM_EVENT;
        HUB_DRIVER_EXIT_CRITICAL();
    }
}

// ------------------------------------------------- Event Handling ----------------------------------------------------

// ---------------------- Callbacks ------------------------

static bool root_port_callback(hcd_port_handle_t port_hdl, hcd_port_event_t port_event, void *user_arg, bool in_isr)
{
    HUB_DRIVER_ENTER_CRITICAL_SAFE();
    p_hub_driver_obj->dynamic.flags.actions |= HUB_DRIVER_FLAG_ACTION_ROOT_EVENT;
    HUB_DRIVER_EXIT_CRITICAL_SAFE();
    assert(in_isr); //Currently, this callback should only ever be called from an ISR context
    return p_hub_driver_obj->constant.notif_cb(USB_NOTIF_SOURCE_HUB, in_isr, p_hub_driver_obj->constant.notif_cb_arg);;
}

static bool enum_dflt_pipe_callback(hcd_pipe_handle_t pipe_hdl, hcd_pipe_event_t pipe_event, void *user_arg, bool in_isr)
{
    //Note: This callback may have triggered when a failed enumeration is already cleaned up (e.g., due to a failed port reset)
    HUB_DRIVER_ENTER_CRITICAL_SAFE();
    p_hub_driver_obj->dynamic.flags.actions |= HUB_DRIVER_FLAG_ACTION_ENUM_EVENT;
    HUB_DRIVER_EXIT_CRITICAL_SAFE();
    return p_hub_driver_obj->constant.notif_cb(USB_NOTIF_SOURCE_HUB, in_isr, p_hub_driver_obj->constant.notif_cb_arg);
}

static void usbh_hub_req_callback(hcd_port_handle_t port_hdl, usbh_hub_req_t hub_req, void *arg)
{
    //We currently only support the root port, so the port_hdl should match the root port
    assert(port_hdl == p_hub_driver_obj->constant.root_port_hdl);

    HUB_DRIVER_ENTER_CRITICAL();
    switch (hub_req) {
        case USBH_HUB_REQ_PORT_DISABLE:
            p_hub_driver_obj->dynamic.flags.actions |= HUB_DRIVER_FLAG_ACTION_PORT_DISABLE;
            break;
        case USBH_HUB_REQ_PORT_RECOVER:
            p_hub_driver_obj->dynamic.flags.actions |= HUB_DRIVER_FLAG_ACTION_PORT_RECOVER;
            break;
        default:
            //Should never occur
            abort();
            break;
    }
    HUB_DRIVER_EXIT_CRITICAL();

    p_hub_driver_obj->constant.notif_cb(USB_NOTIF_SOURCE_HUB, false, p_hub_driver_obj->constant.notif_cb_arg);
}

// ---------------------- Handlers -------------------------

static void root_port_handle_events(hcd_port_handle_t root_port_hdl)
{
    hcd_port_event_t port_event = hcd_port_handle_event(root_port_hdl);
    switch (port_event) {
        case HCD_PORT_EVENT_NONE:
            //Nothing to do
            break;
        case HCD_PORT_EVENT_CONNECTION: {
            if (hcd_port_command(root_port_hdl, HCD_PORT_CMD_RESET) == ESP_OK) {
                ESP_LOGD(HUB_DRIVER_TAG, "Root port reset");
                //Start enumeration
                HUB_DRIVER_ENTER_CRITICAL();
                p_hub_driver_obj->dynamic.flags.actions |= HUB_DRIVER_FLAG_ACTION_ENUM_EVENT;
                p_hub_driver_obj->dynamic.driver_state = HUB_DRIVER_STATE_ROOT_ENUM;
                HUB_DRIVER_EXIT_CRITICAL();
                p_hub_driver_obj->single_thread.enum_ctrl.stage = ENUM_STAGE_START;
            } else {
                ESP_LOGE(HUB_DRIVER_TAG, "Root port reset failed");
            }
            break;
        }
        case HCD_PORT_EVENT_DISCONNECTION:
        case HCD_PORT_EVENT_ERROR:
        case HCD_PORT_EVENT_OVERCURRENT: {
            bool pass_event_to_usbh = false;
            HUB_DRIVER_ENTER_CRITICAL();
            switch (p_hub_driver_obj->dynamic.driver_state) {
                case HUB_DRIVER_STATE_ROOT_POWERED: //This occurred before enumeration
                case HUB_DRIVER_STATE_ROOT_ENUM_FAILED: //This occurred after a failed enumeration.
                    //Therefore, there's no device and we can go straight to port recovery
                    p_hub_driver_obj->dynamic.flags.actions |= HUB_DRIVER_FLAG_ACTION_PORT_RECOVER;
                    break;
                case HUB_DRIVER_STATE_ROOT_ENUM:
                    //This occurred during enumeration. Therefore, we need to recover the failed enumeration
                    p_hub_driver_obj->dynamic.flags.actions |= HUB_DRIVER_FLAG_ACTION_ENUM_EVENT;
                    p_hub_driver_obj->single_thread.enum_ctrl.stage = ENUM_STAGE_CLEANUP_FAILED;
                    break;
                case HUB_DRIVER_STATE_ROOT_ACTIVE:
                    //There was an enumerated device. We need to indicate to USBH that the device is gone
                    pass_event_to_usbh = true;
                    break;
                default:
                    abort();    //Should never occur
                    break;
            }
            p_hub_driver_obj->dynamic.driver_state = HUB_DRIVER_STATE_ROOT_RECOVERY;
            HUB_DRIVER_EXIT_CRITICAL();
            if (pass_event_to_usbh) {
                assert(p_hub_driver_obj->single_thread.root_dev_hdl);
                ESP_ERROR_CHECK(usbh_hub_pass_event(p_hub_driver_obj->single_thread.root_dev_hdl, USBH_HUB_EVENT_PORT_ERROR));
            }
            break;
        }
        default:
            abort();    //Should never occur
            break;
    }
}

static void enum_handle_events(void)
{
    bool stage_pass;
    enum_ctrl_t *enum_ctrl = &p_hub_driver_obj->single_thread.enum_ctrl;
    switch (enum_ctrl->stage) {
        case ENUM_STAGE_START:
            stage_pass = enum_stage_start(enum_ctrl);
            break;
        case ENUM_STAGE_SECOND_RESET:
            stage_pass = enum_stage_second_reset(enum_ctrl);
            break;
        //Transfer submission stages
        case ENUM_STAGE_GET_SHORT_DEV_DESC:
        case ENUM_STAGE_SET_ADDR:
        case ENUM_STAGE_GET_FULL_DEV_DESC:
        case ENUM_STAGE_GET_SHORT_CONFIG_DESC:
        case ENUM_STAGE_GET_FULL_CONFIG_DESC:
        case ENUM_STAGE_SET_CONFIG:
        case ENUM_STAGE_GET_SHORT_LANGID_TABLE:
        case ENUM_STAGE_GET_FULL_LANGID_TABLE:
        case ENUM_STAGE_GET_SHORT_MANU_STR_DESC:
        case ENUM_STAGE_GET_FULL_MANU_STR_DESC:
        case ENUM_STAGE_GET_SHORT_PROD_STR_DESC:
        case ENUM_STAGE_GET_FULL_PROD_STR_DESC:
        case ENUM_STAGE_GET_SHORT_SER_STR_DESC:
        case ENUM_STAGE_GET_FULL_SER_STR_DESC:
            stage_pass = enum_stage_transfer(enum_ctrl);
            break;
        //Transfer check stages
        case ENUM_STAGE_CHECK_SHORT_DEV_DESC:
        case ENUM_STAGE_CHECK_ADDR:
        case ENUM_STAGE_CHECK_FULL_DEV_DESC:
        case ENUM_STAGE_CHECK_SHORT_CONFIG_DESC:
        case ENUM_STAGE_CHECK_FULL_CONFIG_DESC:
        case ENUM_STAGE_CHECK_CONFIG:
        case ENUM_STAGE_CHECK_SHORT_LANGID_TABLE:
        case ENUM_STAGE_CHECK_FULL_LANGID_TABLE:
        case ENUM_STAGE_CHECK_SHORT_MANU_STR_DESC:
        case ENUM_STAGE_CHECK_FULL_MANU_STR_DESC:
        case ENUM_STAGE_CHECK_SHORT_PROD_STR_DESC:
        case ENUM_STAGE_CHECK_FULL_PROD_STR_DESC:
        case ENUM_STAGE_CHECK_SHORT_SER_STR_DESC:
        case ENUM_STAGE_CHECK_FULL_SER_STR_DESC:
            stage_pass = enum_stage_transfer_check(enum_ctrl);
            break;
        case ENUM_STAGE_CLEANUP:
            enum_stage_cleanup(enum_ctrl);
            stage_pass = true;
            break;
        case ENUM_STAGE_CLEANUP_FAILED:
            enum_stage_cleanup_failed(enum_ctrl);
            stage_pass = true;
            break;
        default:
            //Note: Don't abort here. The enum_dflt_pipe_callback() can trigger a HUB_DRIVER_FLAG_ACTION_ENUM_EVENT after a cleanup.
            stage_pass = true;
            break;
    }
    if (stage_pass) {
        ESP_LOGD(HUB_DRIVER_TAG, "Stage done: %s", enum_stage_strings[enum_ctrl->stage]);
    } else {
        ESP_LOGE(HUB_DRIVER_TAG, "Stage failed: %s", enum_stage_strings[enum_ctrl->stage]);
    }
    enum_set_next_stage(enum_ctrl, stage_pass);
}

// ---------------------------------------------- Hub Driver Functions -------------------------------------------------

esp_err_t hub_install(hub_config_t *hub_config)
{
    HUB_DRIVER_ENTER_CRITICAL();
    HUB_DRIVER_CHECK_FROM_CRIT(p_hub_driver_obj == NULL, ESP_ERR_INVALID_STATE);
    HUB_DRIVER_EXIT_CRITICAL();
    //Allocate Hub driver object
    hub_driver_t *hub_driver_obj = heap_caps_calloc(1, sizeof(hub_driver_t), MALLOC_CAP_DEFAULT);
    urb_t *enum_urb = urb_alloc(sizeof(usb_setup_packet_t) + ENUM_CTRL_TRANSFER_MAX_DATA_LEN, 0, 0);
    if (hub_driver_obj == NULL || enum_urb == NULL) {
        return ESP_ERR_NO_MEM;
    }
    esp_err_t ret;
    //Install HCD port
    hcd_port_config_t port_config = {
        .fifo_bias = HUB_ROOT_HCD_PORT_FIFO_BIAS,
        .callback = root_port_callback,
        .callback_arg = NULL,
        .context = NULL,
    };
    hcd_port_handle_t port_hdl;
    ret = hcd_port_init(HUB_ROOT_PORT_NUM, &port_config, &port_hdl);
    if (ret != ESP_OK) {
        goto err;
    }
    //Initialize Hub driver object
    hub_driver_obj->dynamic.driver_state = HUB_DRIVER_STATE_INSTALLED;
    hub_driver_obj->single_thread.enum_ctrl.stage = ENUM_STAGE_NONE;
    hub_driver_obj->single_thread.enum_ctrl.urb = enum_urb;
    hub_driver_obj->constant.root_port_hdl = port_hdl;
    hub_driver_obj->constant.notif_cb = hub_config->notif_cb;
    hub_driver_obj->constant.notif_cb_arg = hub_config->notif_cb_arg;
    HUB_DRIVER_ENTER_CRITICAL();
    if (p_hub_driver_obj != NULL) {
        HUB_DRIVER_EXIT_CRITICAL();
        ret = ESP_ERR_INVALID_STATE;
        goto assign_err;
    }
    p_hub_driver_obj = hub_driver_obj;
    HUB_DRIVER_EXIT_CRITICAL();
    //Indicate to USBH that the hub is installed
    ESP_ERROR_CHECK(usbh_hub_is_installed(usbh_hub_req_callback, NULL));
    ret = ESP_OK;
    return ret;

assign_err:
    ESP_ERROR_CHECK(hcd_port_deinit(port_hdl));
err:
    urb_free(enum_urb);
    heap_caps_free(hub_driver_obj);
    return ret;
}

esp_err_t hub_uninstall(void)
{
    HUB_DRIVER_ENTER_CRITICAL();
    HUB_DRIVER_CHECK_FROM_CRIT(p_hub_driver_obj != NULL, ESP_ERR_INVALID_STATE);
    HUB_DRIVER_CHECK_FROM_CRIT(p_hub_driver_obj->dynamic.driver_state == HUB_DRIVER_STATE_INSTALLED, ESP_ERR_INVALID_STATE);
    hub_driver_t *hub_driver_obj = p_hub_driver_obj;
    p_hub_driver_obj = NULL;
    HUB_DRIVER_EXIT_CRITICAL();

    ESP_ERROR_CHECK(hcd_port_deinit(hub_driver_obj->constant.root_port_hdl));
    //Free Hub driver resources
    urb_free(hub_driver_obj->single_thread.enum_ctrl.urb);
    heap_caps_free(hub_driver_obj);
    return ESP_OK;
}

esp_err_t hub_root_start(void)
{
    HUB_DRIVER_ENTER_CRITICAL();
    HUB_DRIVER_CHECK_FROM_CRIT(p_hub_driver_obj != NULL, ESP_ERR_INVALID_STATE);
    HUB_DRIVER_CHECK_FROM_CRIT(p_hub_driver_obj->dynamic.driver_state == HUB_DRIVER_STATE_INSTALLED, ESP_ERR_INVALID_STATE);
    HUB_DRIVER_EXIT_CRITICAL();
    //Power ON the root port
    esp_err_t ret;
    ret = hcd_port_command(p_hub_driver_obj->constant.root_port_hdl, HCD_PORT_CMD_POWER_ON);
    if (ret == ESP_OK) {
        HUB_DRIVER_ENTER_CRITICAL();
        p_hub_driver_obj->dynamic.driver_state = HUB_DRIVER_STATE_ROOT_POWERED;
        HUB_DRIVER_EXIT_CRITICAL();
    }
    return ret;
}

esp_err_t hub_root_stop(void)
{
    HUB_DRIVER_ENTER_CRITICAL();
    HUB_DRIVER_CHECK_FROM_CRIT(p_hub_driver_obj != NULL, ESP_ERR_INVALID_STATE);
    HUB_DRIVER_CHECK_FROM_CRIT(p_hub_driver_obj->dynamic.driver_state != HUB_DRIVER_STATE_INSTALLED, ESP_ERR_INVALID_STATE);
    HUB_DRIVER_EXIT_CRITICAL();
    esp_err_t ret;
    ret = hcd_port_command(p_hub_driver_obj->constant.root_port_hdl, HCD_PORT_CMD_POWER_OFF);
    if (ret == ESP_OK) {
        HUB_DRIVER_ENTER_CRITICAL();
        p_hub_driver_obj->dynamic.driver_state = HUB_DRIVER_STATE_INSTALLED;
        HUB_DRIVER_EXIT_CRITICAL();
    }
    return ret;
}

esp_err_t hub_process(void)
{
    HUB_DRIVER_ENTER_CRITICAL();
    uint32_t action_flags = p_hub_driver_obj->dynamic.flags.actions;
    p_hub_driver_obj->dynamic.flags.actions = 0;
    HUB_DRIVER_EXIT_CRITICAL();

    while (action_flags) {
        /*
        Mutually exclude Root event and Port disable:
        If a device was waiting for its port to be disabled, and a port error occurs in that time, the root event
        handler will send a USBH_HUB_EVENT_PORT_ERROR to the USBH already, thus freeing the device and canceling the
        waiting of port disable.
        */
        if (action_flags & HUB_DRIVER_FLAG_ACTION_ROOT_EVENT) {
            root_port_handle_events(p_hub_driver_obj->constant.root_port_hdl);
        } else if (action_flags & HUB_DRIVER_FLAG_ACTION_PORT_DISABLE) {
            ESP_LOGD(HUB_DRIVER_TAG, "Disabling root port");
            hcd_port_command(p_hub_driver_obj->constant.root_port_hdl, HCD_PORT_CMD_DISABLE);
            ESP_ERROR_CHECK(usbh_hub_pass_event(p_hub_driver_obj->single_thread.root_dev_hdl, USBH_HUB_EVENT_PORT_DISABLED));
            //The root port has been disabled, so the root_dev_hdl is no longer valid
            p_hub_driver_obj->single_thread.root_dev_hdl = NULL;
        }

        if (action_flags & HUB_DRIVER_FLAG_ACTION_PORT_RECOVER) {
            ESP_LOGD(HUB_DRIVER_TAG, "Recovering root port");
            ESP_ERROR_CHECK(hcd_port_recover(p_hub_driver_obj->constant.root_port_hdl));
            ESP_ERROR_CHECK(hcd_port_command(p_hub_driver_obj->constant.root_port_hdl, HCD_PORT_CMD_POWER_ON));
            HUB_DRIVER_ENTER_CRITICAL();
            p_hub_driver_obj->dynamic.driver_state = HUB_DRIVER_STATE_ROOT_POWERED;
            HUB_DRIVER_EXIT_CRITICAL();
            //USBH requesting a port recovery means the device has already been freed. Clear root_dev_hdl
            p_hub_driver_obj->single_thread.root_dev_hdl = NULL;
        }

        if (action_flags & HUB_DRIVER_FLAG_ACTION_ENUM_EVENT) {
            enum_handle_events();
        }

        HUB_DRIVER_ENTER_CRITICAL();
        action_flags = p_hub_driver_obj->dynamic.flags.actions;
        p_hub_driver_obj->dynamic.flags.actions = 0;
        HUB_DRIVER_EXIT_CRITICAL();
    }
    return ESP_OK;
}