Merge tag 'usb-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB/Thunderbolt updates from Greg KH:
 "Here is the large set of USB and Thunderbolt patches for 5.9-rc1.

  Nothing really magic/major in here, just lots of little changes and
  updates:

   - clean up language usages in USB core and some drivers

   - Thunderbolt driver updates and additions

   - USB Gadget driver updates

   - dwc3 driver updates (like always...)

   - build with "W=1" warning fixups

   - mtu3 driver updates

   - usb-serial driver updates and device ids

   - typec additions and updates for new hardware

   - xhci debug code updates for future platforms

   - cdns3 driver updates

   - lots of other minor driver updates and fixes and cleanups

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'usb-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (330 commits)
  usb: common: usb-conn-gpio: Register charger
  usb: mtu3: simplify mtu3_req_complete()
  usb: mtu3: clear dual mode of u3port when disable device
  usb: mtu3: use MTU3_EP_WEDGE flag
  usb: mtu3: remove useless member @busy in mtu3_ep struct
  usb: mtu3: remove repeated error log
  usb: mtu3: add ->udc_set_speed()
  usb: mtu3: introduce a funtion to check maximum speed
  usb: mtu3: clear interrupts status when disable interrupts
  usb: mtu3: reinitialize CSR registers
  usb: mtu3: fix macro for maximum number of packets
  usb: mtu3: remove unnecessary pointer checks
  usb: xhci: Fix ASMedia ASM1142 DMA addressing
  usb: xhci: define IDs for various ASMedia host controllers
  usb: musb: convert to devm_platform_ioremap_resource_byname
  usb: gadget: tegra-xudc: convert to devm_platform_ioremap_resource_byname
  usb: gadget: r8a66597: convert to devm_platform_ioremap_resource_byname
  usb: dwc3: convert to devm_platform_ioremap_resource_byname
  usb: cdns3: convert to devm_platform_ioremap_resource_byname
  usb: phy: am335x: convert to devm_platform_ioremap_resource_byname
  ...

14 files changed, 108 insertions, 80 deletions

diff --git a/include/linux/thunderbolt.h b/include/linux/thunderbolt.h
index ff397c0d5c07..5db2b11ab085 100644
--- a/include/linux/thunderbolt.h
+++ b/include/linux/thunderbolt.h
@@ -504,8 +504,6 @@ struct tb_ring {
 #define RING_FLAG_NO_SUSPEND	BIT(0)
 /* Configure the ring to be in frame mode */
 #define RING_FLAG_FRAME		BIT(1)
-/* Enable end-to-end flow control */
-#define RING_FLAG_E2E		BIT(2)
 
 struct ring_frame;
 typedef void (*ring_cb)(struct tb_ring *, struct ring_frame *, bool canceled);
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 9f3c721c70dc..20c555db4621 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -341,7 +341,7 @@ struct usb_interface_cache {
  * @interface: array of pointers to usb_interface structures, one for each
  *	interface in the configuration.  The number of interfaces is stored
  *	in desc.bNumInterfaces.  These pointers are valid only while the
- *	the configuration is active.
+ *	configuration is active.
  * @intf_cache: array of pointers to usb_interface_cache structures, one
  *	for each interface in the configuration.  These structures exist
  *	for the entire life of the device.
@@ -422,7 +422,7 @@ struct usb_devmap {
  * Allocated per bus (tree of devices) we have:
  */
 struct usb_bus {
-	struct device *controller;	/* host/master side hardware */
+	struct device *controller;	/* host side hardware */
 	struct device *sysdev;		/* as seen from firmware or bus */
 	int busnum;			/* Bus number (in order of reg) */
 	const char *bus_name;		/* stable id (PCI slot_name etc) */
@@ -620,9 +620,9 @@ struct usb3_lpm_parameters {
  *	Management to be disabled for this usb_device.  This count should only
  *	be manipulated by those functions, with the bandwidth_mutex is held.
  * @hub_delay: cached value consisting of:
- *		parent->hub_delay + wHubDelay + tTPTransmissionDelay (40ns)
- *
+ *	parent->hub_delay + wHubDelay + tTPTransmissionDelay (40ns)
  *	Will be used as wValue for SetIsochDelay requests.
+ * @use_generic_driver: ask driver core to reprobe using the generic driver.
  *
  * Notes:
  * Usbcore drivers should not set usbdev->state directly.  Instead use
@@ -1215,6 +1215,7 @@ struct usb_driver {
  * struct usb_device_driver - identifies USB device driver to usbcore
  * @name: The driver name should be unique among USB drivers,
  *	and should normally be the same as the module name.
+ * @match: If set, used for better device/driver matching.
  * @probe: Called to see if the driver is willing to manage a particular
  *	device.  If it is, probe returns zero and uses dev_set_drvdata()
  *	to associate driver-specific data with the device.  If unwilling
@@ -1227,13 +1228,16 @@ struct usb_driver {
  * @dev_groups: Attributes attached to the device that will be created once it
  *	is bound to the driver.
  * @drvwrap: Driver-model core structure wrapper.
+ * @id_table: used with @match() to select better matching driver at
+ * 	probe() time.
  * @supports_autosuspend: if set to 0, the USB core will not allow autosuspend
  *	for devices bound to this driver.
  * @generic_subclass: if set to 1, the generic USB driver's probe, disconnect,
  *	resume and suspend functions will be called in addition to the driver's
  *	own, so this part of the setup does not need to be replicated.
  *
- * USB drivers must provide all the fields listed above except drvwrap.
+ * USB drivers must provide all the fields listed above except drvwrap,
+ * match, and id_table.
  */
 struct usb_device_driver {
 	const char *name;
diff --git a/include/linux/usb/ch9.h b/include/linux/usb/ch9.h
index 58b83066bea4..604c6c514a50 100644
--- a/include/linux/usb/ch9.h
+++ b/include/linux/usb/ch9.h
@@ -6,13 +6,13 @@
  * Wireless USB 1.0 (spread around).  Linux has several APIs in C that
  * need these:
  *
- * - the master/host side Linux-USB kernel driver API;
+ * - the host side Linux-USB kernel driver API;
  * - the "usbfs" user space API; and
- * - the Linux "gadget" slave/device/peripheral side driver API.
+ * - the Linux "gadget" device/peripheral side driver API.
  *
  * USB 2.0 adds an additional "On The Go" (OTG) mode, which lets systems
- * act either as a USB master/host or as a USB slave/device.  That means
- * the master and slave side APIs benefit from working well together.
+ * act either as a USB host or as a USB device.  That means the host and
+ * device side APIs benefit from working well together.
  *
  * There's also "Wireless USB", using low power short range radios for
  * peripheral interconnection but otherwise building on the USB framework.
diff --git a/include/linux/usb/chipidea.h b/include/linux/usb/chipidea.h
index 54167a2d28ea..025b41687ce9 100644
--- a/include/linux/usb/chipidea.h
+++ b/include/linux/usb/chipidea.h
@@ -99,5 +99,7 @@ struct platform_device *ci_hdrc_add_device(struct device *dev,
 			struct ci_hdrc_platform_data *platdata);
 /* Remove ci hdrc device */
 void ci_hdrc_remove_device(struct platform_device *pdev);
+/* Get current available role */
+enum usb_dr_mode ci_hdrc_query_available_role(struct platform_device *pdev);
 
 #endif
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 6a178177e4c9..52ce1f6b8f83 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -4,7 +4,8 @@
  *
  * We call the USB code inside a Linux-based peripheral device a "gadget"
  * driver, except for the hardware-specific bus glue.  One USB host can
- * master many USB gadgets, but the gadgets are only slaved to one host.
+ * talk to many USB gadgets, but the gadgets are only able to communicate
+ * to one host.
  *
  *
  * (C) Copyright 2002-2004 by David Brownell
@@ -328,7 +329,7 @@ struct usb_gadget_ops {
 };
 
 /**
- * struct usb_gadget - represents a usb slave device
+ * struct usb_gadget - represents a usb device
  * @work: (internal use) Workqueue to be used for sysfs_notify()
  * @udc: struct usb_udc pointer for this gadget
  * @ops: Function pointers used to access hardware-specific operations.
@@ -602,7 +603,7 @@ static inline int usb_gadget_activate(struct usb_gadget *gadget)
 /*-------------------------------------------------------------------------*/
 
 /**
- * struct usb_gadget_driver - driver for usb 'slave' devices
+ * struct usb_gadget_driver - driver for usb gadget devices
  * @function: String describing the gadget's function
  * @max_speed: Highest speed the driver handles.
  * @setup: Invoked for ep0 control requests that aren't handled by
@@ -730,7 +731,7 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver);
  * it will first disconnect().  The driver is also requested
  * to unbind() and clean up any device state, before this procedure
  * finally returns.  It's expected that the unbind() functions
- * will in in exit sections, so may not be linked in some kernels.
+ * will be in exit sections, so may not be linked in some kernels.
  */
 int usb_gadget_unregister_driver(struct usb_gadget_driver *driver);
 
diff --git a/include/linux/usb/pd.h b/include/linux/usb/pd.h
index a665d7f21142..b6c233e79bd4 100644
--- a/include/linux/usb/pd.h
+++ b/include/linux/usb/pd.h
@@ -483,4 +483,5 @@ static inline unsigned int rdo_max_power(u32 rdo)
 #define PD_N_CAPS_COUNT		(PD_T_NO_RESPONSE / PD_T_SEND_SOURCE_CAP)
 #define PD_N_HARD_RESET_COUNT	2
 
+#define PD_T_BIST_CONT_MODE	50 /* 30 - 60 ms */
 #endif /* __LINUX_USB_PD_H */
diff --git a/include/linux/usb/pd_vdo.h b/include/linux/usb/pd_vdo.h
index 35b8e15efaa0..68bdc4e2f5a9 100644
--- a/include/linux/usb/pd_vdo.h
+++ b/include/linux/usb/pd_vdo.h
@@ -249,7 +249,7 @@
  * SVDM Discover SVIDs request -> response
  *
  * Request is properly formatted VDM Header with discover SVIDs command.
- * Response is a set of SVIDs of all all supported SVIDs with all zero's to
+ * Response is a set of SVIDs of all supported SVIDs with all zero's to
  * mark the end of SVIDs.  If more than 12 SVIDs are supported command SHOULD be
  * repeated.
  */
diff --git a/include/linux/usb/phy_companion.h b/include/linux/usb/phy_companion.h
index 407f530061cd..263196f05015 100644
--- a/include/linux/usb/phy_companion.h
+++ b/include/linux/usb/phy_companion.h
@@ -2,7 +2,7 @@
 /*
  * phy-companion.h -- phy companion to indicate the comparator part of PHY
  *
- * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com
+ * Copyright (C) 2012 Texas Instruments Incorporated - https://www.ti.com
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
diff --git a/include/linux/usb/quirks.h b/include/linux/usb/quirks.h
index 22c1f579afe3..5e4c497f54d6 100644
--- a/include/linux/usb/quirks.h
+++ b/include/linux/usb/quirks.h
@@ -69,7 +69,7 @@
 /* Hub needs extra delay after resetting its port. */
 #define USB_QUIRK_HUB_SLOW_RESET		BIT(14)
 
-/* device has blacklisted endpoints */
-#define USB_QUIRK_ENDPOINT_BLACKLIST		BIT(15)
+/* device has endpoints that should be ignored */
+#define USB_QUIRK_ENDPOINT_IGNORE		BIT(15)
 
 #endif /* __LINUX_USB_QUIRKS_H */
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 14cac4a1ae8f..8e67eff9039f 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -17,7 +17,6 @@
 #include <linux/kref.h>
 #include <linux/mutex.h>
 #include <linux/serial.h>
-#include <linux/sysrq.h>
 #include <linux/kfifo.h>
 
 /* The maximum number of ports one device can grab at once */
@@ -213,7 +212,7 @@ struct usb_serial_endpoints {
  *	Return 0 to continue on with the initialization sequence.  Anything
  *	else will abort it.
  * @attach: pointer to the driver's attach function.
- *	This will be called when the struct usb_serial structure is fully set
+ *	This will be called when the struct usb_serial structure is fully
  *	set up.  Do any local initialization of the device, or any private
  *	memory structure allocation at this point in time.
  * @disconnect: pointer to the driver's disconnect function.  This will be
@@ -316,19 +315,19 @@ struct usb_serial_driver {
 #define to_usb_serial_driver(d) \
 	container_of(d, struct usb_serial_driver, driver)
 
-extern int usb_serial_register_drivers(struct usb_serial_driver *const serial_drivers[],
+int usb_serial_register_drivers(struct usb_serial_driver *const serial_drivers[],
 		const char *name, const struct usb_device_id *id_table);
-extern void usb_serial_deregister_drivers(struct usb_serial_driver *const serial_drivers[]);
-extern void usb_serial_port_softint(struct usb_serial_port *port);
+void usb_serial_deregister_drivers(struct usb_serial_driver *const serial_drivers[]);
+void usb_serial_port_softint(struct usb_serial_port *port);
 
-extern int usb_serial_suspend(struct usb_interface *intf, pm_message_t message);
-extern int usb_serial_resume(struct usb_interface *intf);
+int usb_serial_suspend(struct usb_interface *intf, pm_message_t message);
+int usb_serial_resume(struct usb_interface *intf);
 
 /* USB Serial console functions */
 #ifdef CONFIG_USB_SERIAL_CONSOLE
-extern void usb_serial_console_init(int minor);
-extern void usb_serial_console_exit(void);
-extern void usb_serial_console_disconnect(struct usb_serial *serial);
+void usb_serial_console_init(int minor);
+void usb_serial_console_exit(void);
+void usb_serial_console_disconnect(struct usb_serial *serial);
 #else
 static inline void usb_serial_console_init(int minor) { }
 static inline void usb_serial_console_exit(void) { }
@@ -336,45 +335,49 @@ static inline void usb_serial_console_disconnect(struct usb_serial *serial) {}
 #endif
 
 /* Functions needed by other parts of the usbserial core */
-extern struct usb_serial_port *usb_serial_port_get_by_minor(unsigned int minor);
-extern void usb_serial_put(struct usb_serial *serial);
-extern int usb_serial_generic_open(struct tty_struct *tty,
-	struct usb_serial_port *port);
-extern int usb_serial_generic_write_start(struct usb_serial_port *port,
-							gfp_t mem_flags);
-extern int usb_serial_generic_write(struct tty_struct *tty,
-	struct usb_serial_port *port, const unsigned char *buf, int count);
-extern void usb_serial_generic_close(struct usb_serial_port *port);
-extern int usb_serial_generic_resume(struct usb_serial *serial);
-extern int usb_serial_generic_write_room(struct tty_struct *tty);
-extern int usb_serial_generic_chars_in_buffer(struct tty_struct *tty);
-extern void usb_serial_generic_wait_until_sent(struct tty_struct *tty,
-								long timeout);
-extern void usb_serial_generic_read_bulk_callback(struct urb *urb);
-extern void usb_serial_generic_write_bulk_callback(struct urb *urb);
-extern void usb_serial_generic_throttle(struct tty_struct *tty);
-extern void usb_serial_generic_unthrottle(struct tty_struct *tty);
-extern int usb_serial_generic_tiocmiwait(struct tty_struct *tty,
-							unsigned long arg);
-extern int usb_serial_generic_get_icount(struct tty_struct *tty,
-					struct serial_icounter_struct *icount);
-extern int usb_serial_generic_register(void);
-extern void usb_serial_generic_deregister(void);
-extern int usb_serial_generic_submit_read_urbs(struct usb_serial_port *port,
-						 gfp_t mem_flags);
-extern void usb_serial_generic_process_read_urb(struct urb *urb);
-extern int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port,
-						void *dest, size_t size);
-extern int usb_serial_handle_sysrq_char(struct usb_serial_port *port,
-					unsigned int ch);
-extern int usb_serial_handle_break(struct usb_serial_port *port);
-extern void usb_serial_handle_dcd_change(struct usb_serial_port *usb_port,
-					 struct tty_struct *tty,
-					 unsigned int status);
+struct usb_serial_port *usb_serial_port_get_by_minor(unsigned int minor);
+void usb_serial_put(struct usb_serial *serial);
+int usb_serial_generic_open(struct tty_struct *tty, struct usb_serial_port *port);
+int usb_serial_generic_write_start(struct usb_serial_port *port, gfp_t mem_flags);
+int usb_serial_generic_write(struct tty_struct *tty, struct usb_serial_port *port,
+		const unsigned char *buf, int count);
+void usb_serial_generic_close(struct usb_serial_port *port);
+int usb_serial_generic_resume(struct usb_serial *serial);
+int usb_serial_generic_write_room(struct tty_struct *tty);
+int usb_serial_generic_chars_in_buffer(struct tty_struct *tty);
+void usb_serial_generic_wait_until_sent(struct tty_struct *tty, long timeout);
+void usb_serial_generic_read_bulk_callback(struct urb *urb);
+void usb_serial_generic_write_bulk_callback(struct urb *urb);
+void usb_serial_generic_throttle(struct tty_struct *tty);
+void usb_serial_generic_unthrottle(struct tty_struct *tty);
+int usb_serial_generic_tiocmiwait(struct tty_struct *tty, unsigned long arg);
+int usb_serial_generic_get_icount(struct tty_struct *tty, struct serial_icounter_struct *icount);
+int usb_serial_generic_register(void);
+void usb_serial_generic_deregister(void);
+int usb_serial_generic_submit_read_urbs(struct usb_serial_port *port, gfp_t mem_flags);
+void usb_serial_generic_process_read_urb(struct urb *urb);
+int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port, void *dest, size_t size);
+
+#if defined(CONFIG_USB_SERIAL_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch);
+int usb_serial_handle_break(struct usb_serial_port *port);
+#else
+static inline int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch)
+{
+	return 0;
+}
+static inline int usb_serial_handle_break(struct usb_serial_port *port)
+{
+	return 0;
+}
+#endif
+
+void usb_serial_handle_dcd_change(struct usb_serial_port *usb_port,
+		struct tty_struct *tty, unsigned int status);
 
 
-extern int usb_serial_bus_register(struct usb_serial_driver *device);
-extern void usb_serial_bus_deregister(struct usb_serial_driver *device);
+int usb_serial_bus_register(struct usb_serial_driver *device);
+void usb_serial_bus_deregister(struct usb_serial_driver *device);
 
 extern struct bus_type usb_serial_bus_type;
 extern struct tty_driver *usb_serial_tty_driver;
diff --git a/include/linux/usb/tcpm.h b/include/linux/usb/tcpm.h
index e7979c01c351..89f58760cf48 100644
--- a/include/linux/usb/tcpm.h
+++ b/include/linux/usb/tcpm.h
@@ -79,6 +79,7 @@ enum tcpm_transmit_type {
  * @try_role:	Optional; called to set a preferred role
  * @pd_transmit:Called to transmit PD message
  * @mux:	Pointer to multiplexer data
+ * @set_bist_data: Turn on/off bist data mode for compliance testing
  */
 struct tcpc_dev {
 	struct fwnode_handle *fwnode;
@@ -103,6 +104,7 @@ struct tcpc_dev {
 	int (*try_role)(struct tcpc_dev *dev, int role);
 	int (*pd_transmit)(struct tcpc_dev *dev, enum tcpm_transmit_type type,
 			   const struct pd_message *msg);
+	int (*set_bist_data)(struct tcpc_dev *dev, bool on);
 };
 
 struct tcpm_port;
diff --git a/include/linux/usb/typec.h b/include/linux/usb/typec.h
index 5daa1c49761c..9cb1bec94b71 100644
--- a/include/linux/usb/typec.h
+++ b/include/linux/usb/typec.h
@@ -73,6 +73,20 @@ enum typec_orientation {
 };
 
 /*
+ * struct enter_usb_data - Enter_USB Message details
+ * @eudo: Enter_USB Data Object
+ * @active_link_training: Active Cable Plug Link Training
+ *
+ * @active_link_training is a flag that should be set with uni-directional SBRX
+ * communication, and left 0 with passive cables and with bi-directional SBRX
+ * communication.
+ */
+struct enter_usb_data {
+	u32			eudo;
+	unsigned char		active_link_training:1;
+};
+
+/*
  * struct usb_pd_identity - USB Power Delivery identity data
  * @id_header: ID Header VDO
  * @cert_stat: Cert Stat VDO
diff --git a/include/linux/usb/typec_altmode.h b/include/linux/usb/typec_altmode.h
index d834e236c6df..a4b65eaa0f62 100644
--- a/include/linux/usb/typec_altmode.h
+++ b/include/linux/usb/typec_altmode.h
@@ -95,13 +95,7 @@ enum {
  *
  * Port drivers can use TYPEC_MODE_AUDIO and TYPEC_MODE_DEBUG as the mode
  * value for typec_set_mode() when accessory modes are supported.
- */
-enum {
-	TYPEC_MODE_AUDIO = TYPEC_STATE_MODAL,	/* Audio Accessory */
-	TYPEC_MODE_DEBUG,			/* Debug Accessory */
-};
-
-/*
+ *
  * USB4 also requires that the pins on the connector are repurposed, just like
  * Alternate Modes. USB4 mode is however not entered with the Enter Mode Command
  * like the Alternate Modes are, but instead with a special Enter_USB Message.
@@ -112,9 +106,11 @@ enum {
  * state values, just like the Accessory Modes.
  */
 enum {
-	TYPEC_MODE_USB2 = TYPEC_MODE_DEBUG,	/* USB 2.0 mode */
+	TYPEC_MODE_USB2 = TYPEC_STATE_MODAL,	/* USB 2.0 mode */
 	TYPEC_MODE_USB3,			/* USB 3.2 mode */
-	TYPEC_MODE_USB4				/* USB4 mode */
+	TYPEC_MODE_USB4,			/* USB4 mode */
+	TYPEC_MODE_AUDIO,			/* Audio Accessory */
+	TYPEC_MODE_DEBUG,			/* Debug Accessory */
 };
 
 #define TYPEC_MODAL_STATE(_state_)	((_state_) + TYPEC_STATE_MODAL)
diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
index 2b623f36af6b..48766fdf6580 100644
--- a/include/uapi/linux/usb/ch9.h
+++ b/include/uapi/linux/usb/ch9.h
@@ -138,11 +138,11 @@
  * Test Mode Selectors
  * See USB 2.0 spec Table 9-7
  */
-#define	TEST_J		1
-#define	TEST_K		2
-#define	TEST_SE0_NAK	3
-#define	TEST_PACKET	4
-#define	TEST_FORCE_EN	5
+#define	USB_TEST_J		1
+#define	USB_TEST_K		2
+#define	USB_TEST_SE0_NAK	3
+#define	USB_TEST_PACKET		4
+#define	USB_TEST_FORCE_ENABLE	5
 
 /* Status Type */
 #define USB_STATUS_TYPE_STANDARD	0
@@ -326,6 +326,10 @@ struct usb_device_descriptor {
 #define USB_CLASS_CONTENT_SEC		0x0d	/* content security */
 #define USB_CLASS_VIDEO			0x0e
 #define USB_CLASS_WIRELESS_CONTROLLER	0xe0
+#define USB_CLASS_PERSONAL_HEALTHCARE	0x0f
+#define USB_CLASS_AUDIO_VIDEO		0x10
+#define USB_CLASS_BILLBOARD		0x11
+#define USB_CLASS_USB_TYPE_C_BRIDGE	0x12
 #define USB_CLASS_MISC			0xef
 #define USB_CLASS_APP_SPEC		0xfe
 #define USB_CLASS_VENDOR_SPEC		0xff
@@ -364,6 +368,9 @@ struct usb_config_descriptor {
 
 /*-------------------------------------------------------------------------*/
 
+/* USB String descriptors can contain at most 126 characters. */
+#define USB_MAX_STRING_LEN	126
+
 /* USB_DT_STRING: String descriptor */
 struct usb_string_descriptor {
 	__u8  bLength;