Merge tag 'usb-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB / Thunderbolt updates from Greg KH:
 "Here is the big set of USB and Thunderbolt patches for 5.14-rc1.

  Nothing major here just lots of little changes for new hardware and
  features. Highlights are:

   - more USB 4 support added to the thunderbolt core

   - build warning fixes all over the place

   - usb-serial driver updates and new device support

   - mtu3 driver updates

   - gadget driver updates

   - dwc3 driver updates

   - dwc2 driver updates

   - isp1760 host driver updates

   - musb driver updates

   - lots of other tiny things.

  Full details are in the shortlog.

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

* tag 'usb-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (223 commits)
  phy: qcom-qusb2: Add configuration for SM4250 and SM6115
  dt-bindings: phy: qcom,qusb2: document sm4250/6115 compatible
  dt-bindings: usb: qcom,dwc3: Add bindings for sm6115/4250
  USB: cdc-acm: blacklist Heimann USB Appset device
  usb: xhci-mtk: allow multiple Start-Split in a microframe
  usb: ftdi-elan: remove redundant continue statement in a while-loop
  usb: class: cdc-wdm: return the correct errno code
  xhci: remove redundant continue statement
  usb: dwc3: Fix debugfs creation flow
  usb: gadget: hid: fix error return code in hid_bind()
  usb: gadget: eem: fix echo command packet response issue
  usb: gadget: f_hid: fix endianness issue with descriptors
  Revert "USB: misc: Add onboard_usb_hub driver"
  Revert "of/platform: Add stubs for of_platform_device_create/destroy()"
  Revert "usb: host: xhci-plat: Create platform device for onboard hubs in probe()"
  Revert "arm64: dts: qcom: sc7180-trogdor: Add nodes for onboard USB hub"
  xhci: solve a double free problem while doing s4
  xhci: handle failed buffer copy to URB sg list and fix a W=1 copiler warning
  xhci: Add adaptive interrupt rate for isoch TRBs with XHCI_AVOID_BEI quirk
  xhci: Remove unused defines for ERST_SIZE and ERST_ENTRIES
  ...

26 files changed, 169 insertions, 149 deletions

diff --git a/drivers/usb/gadget/udc/bcm63xx_udc.c b/drivers/usb/gadget/udc/bcm63xx_udc.c
index 9cd4a70ccdd6..a9f07c59fc37 100644
--- a/drivers/usb/gadget/udc/bcm63xx_udc.c
+++ b/drivers/usb/gadget/udc/bcm63xx_udc.c
@@ -288,7 +288,6 @@ struct bcm63xx_req {
  * @ep0_req_completed: ep0 request has completed; worker has not seen it yet.
  * @ep0_reply: Pending reply from gadget driver.
  * @ep0_request: Outstanding ep0 request.
- * @debugfs_root: debugfs directory: /sys/kernel/debug/<DRV_MODULE_NAME>.
  */
 struct bcm63xx_udc {
 	spinlock_t			lock;
@@ -327,8 +326,6 @@ struct bcm63xx_udc {
 	unsigned			ep0_req_completed:1;
 	struct usb_request		*ep0_reply;
 	struct usb_request		*ep0_request;
-
-	struct dentry			*debugfs_root;
 };
 
 static const struct usb_ep_ops bcm63xx_udc_ep_ops;
@@ -2250,8 +2247,6 @@ static void bcm63xx_udc_init_debugfs(struct bcm63xx_udc *udc)
 		return;
 
 	root = debugfs_create_dir(udc->gadget.name, usb_debug_root);
-	udc->debugfs_root = root;
-
 	debugfs_create_file("usbd", 0400, root, udc, &bcm63xx_usbd_dbg_fops);
 	debugfs_create_file("iudma", 0400, root, udc, &bcm63xx_iudma_dbg_fops);
 }
@@ -2264,7 +2259,7 @@ static void bcm63xx_udc_init_debugfs(struct bcm63xx_udc *udc)
  */
 static void bcm63xx_udc_cleanup_debugfs(struct bcm63xx_udc *udc)
 {
-	debugfs_remove_recursive(udc->debugfs_root);
+	debugfs_remove(debugfs_lookup(udc->gadget.name, usb_debug_root));
 }
 
 /***********************************************************************
diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 493ff93f7dda..b7f0b1ebaaa8 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1148,6 +1148,53 @@ static inline void usb_gadget_udc_set_speed(struct usb_udc *udc,
 }
 
 /**
+ * usb_gadget_enable_async_callbacks - tell usb device controller to enable asynchronous callbacks
+ * @udc: The UDC which should enable async callbacks
+ *
+ * This routine is used when binding gadget drivers.  It undoes the effect
+ * of usb_gadget_disable_async_callbacks(); the UDC driver should enable IRQs
+ * (if necessary) and resume issuing callbacks.
+ *
+ * This routine will always be called in process context.
+ */
+static inline void usb_gadget_enable_async_callbacks(struct usb_udc *udc)
+{
+	struct usb_gadget *gadget = udc->gadget;
+
+	if (gadget->ops->udc_async_callbacks)
+		gadget->ops->udc_async_callbacks(gadget, true);
+}
+
+/**
+ * usb_gadget_disable_async_callbacks - tell usb device controller to disable asynchronous callbacks
+ * @udc: The UDC which should disable async callbacks
+ *
+ * This routine is used when unbinding gadget drivers.  It prevents a race:
+ * The UDC driver doesn't know when the gadget driver's ->unbind callback
+ * runs, so unless it is told to disable asynchronous callbacks, it might
+ * issue a callback (such as ->disconnect) after the unbind has completed.
+ *
+ * After this function runs, the UDC driver must suppress all ->suspend,
+ * ->resume, ->disconnect, ->reset, and ->setup callbacks to the gadget driver
+ * until async callbacks are again enabled.  A simple-minded but effective
+ * way to accomplish this is to tell the UDC hardware not to generate any
+ * more IRQs.
+ *
+ * Request completion callbacks must still be issued.  However, it's okay
+ * to defer them until the request is cancelled, since the pull-up will be
+ * turned off during the time period when async callbacks are disabled.
+ *
+ * This routine will always be called in process context.
+ */
+static inline void usb_gadget_disable_async_callbacks(struct usb_udc *udc)
+{
+	struct usb_gadget *gadget = udc->gadget;
+
+	if (gadget->ops->udc_async_callbacks)
+		gadget->ops->udc_async_callbacks(gadget, false);
+}
+
+/**
  * usb_udc_release - release the usb_udc struct
  * @dev: the dev member within usb_udc
  *
@@ -1361,6 +1408,7 @@ static void usb_gadget_remove_driver(struct usb_udc *udc)
 	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
 
 	usb_gadget_disconnect(udc->gadget);
+	usb_gadget_disable_async_callbacks(udc);
 	if (udc->gadget->irq)
 		synchronize_irq(udc->gadget->irq);
 	udc->driver->unbind(udc->gadget);
@@ -1442,6 +1490,7 @@ static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *dri
 		driver->unbind(udc->gadget);
 		goto err1;
 	}
+	usb_gadget_enable_async_callbacks(udc);
 	usb_udc_connect_control(udc);
 
 	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
diff --git a/drivers/usb/gadget/udc/dummy_hcd.c b/drivers/usb/gadget/udc/dummy_hcd.c
index 7db773c87379..a2d956af42a2 100644
--- a/drivers/usb/gadget/udc/dummy_hcd.c
+++ b/drivers/usb/gadget/udc/dummy_hcd.c
@@ -934,6 +934,15 @@ static void dummy_udc_set_speed(struct usb_gadget *_gadget,
 	dummy_udc_update_ep0(dum);
 }
 
+static void dummy_udc_async_callbacks(struct usb_gadget *_gadget, bool enable)
+{
+	struct dummy	*dum = gadget_dev_to_dummy(&_gadget->dev);
+
+	spin_lock_irq(&dum->lock);
+	dum->ints_enabled = enable;
+	spin_unlock_irq(&dum->lock);
+}
+
 static int dummy_udc_start(struct usb_gadget *g,
 		struct usb_gadget_driver *driver);
 static int dummy_udc_stop(struct usb_gadget *g);
@@ -946,6 +955,7 @@ static const struct usb_gadget_ops dummy_ops = {
 	.udc_start	= dummy_udc_start,
 	.udc_stop	= dummy_udc_stop,
 	.udc_set_speed	= dummy_udc_set_speed,
+	.udc_async_callbacks = dummy_udc_async_callbacks,
 };
 
 /*-------------------------------------------------------------------------*/
@@ -1005,7 +1015,6 @@ static int dummy_udc_start(struct usb_gadget *g,
 	spin_lock_irq(&dum->lock);
 	dum->devstatus = 0;
 	dum->driver = driver;
-	dum->ints_enabled = 1;
 	spin_unlock_irq(&dum->lock);
 
 	return 0;
diff --git a/drivers/usb/gadget/udc/fsl_qe_udc.c b/drivers/usb/gadget/udc/fsl_qe_udc.c
index fa66449b3907..8e8588933628 100644
--- a/drivers/usb/gadget/udc/fsl_qe_udc.c
+++ b/drivers/usb/gadget/udc/fsl_qe_udc.c
@@ -541,6 +541,7 @@ static int qe_ep_init(struct qe_udc *udc,
 			case USB_SPEED_HIGH:
 			if ((max == 128) || (max == 256) || (max == 512))
 				break;
+			fallthrough;
 			default:
 				switch (max) {
 				case 4:
@@ -562,9 +563,11 @@ static int qe_ep_init(struct qe_udc *udc,
 			case USB_SPEED_HIGH:
 				if (max <= 1024)
 					break;
+				fallthrough;
 			case USB_SPEED_FULL:
 				if (max <= 64)
 					break;
+				fallthrough;
 			default:
 				if (max <= 8)
 					break;
@@ -579,6 +582,7 @@ static int qe_ep_init(struct qe_udc *udc,
 			case USB_SPEED_HIGH:
 				if (max <= 1024)
 					break;
+				fallthrough;
 			case USB_SPEED_FULL:
 				if (max <= 1023)
 					break;
@@ -605,6 +609,7 @@ static int qe_ep_init(struct qe_udc *udc,
 				default:
 					goto en_done;
 				}
+				fallthrough;
 			case USB_SPEED_LOW:
 				switch (max) {
 				case 1:
diff --git a/drivers/usb/gadget/udc/fsl_udc_core.c b/drivers/usb/gadget/udc/fsl_udc_core.c
index ad6ff9c4188e..29fcb9b461d7 100644
--- a/drivers/usb/gadget/udc/fsl_udc_core.c
+++ b/drivers/usb/gadget/udc/fsl_udc_core.c
@@ -36,7 +36,6 @@
 #include <linux/platform_device.h>
 #include <linux/fsl_devices.h>
 #include <linux/dmapool.h>
-#include <linux/delay.h>
 #include <linux/of_device.h>
 
 #include <asm/byteorder.h>
@@ -323,13 +322,11 @@ static int dr_controller_setup(struct fsl_udc *udc)
 		fsl_writel(tmp, &dr_regs->endptctrl[ep_num]);
 	}
 	/* Config control enable i/o output, cpu endian register */
-#ifndef CONFIG_ARCH_MXC
 	if (udc->pdata->have_sysif_regs) {
 		ctrl = __raw_readl(&usb_sys_regs->control);
 		ctrl |= USB_CTRL_IOENB;
 		__raw_writel(ctrl, &usb_sys_regs->control);
 	}
-#endif
 
 #if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
 	/* Turn on cache snooping hardware, since some PowerPC platforms
@@ -547,7 +544,7 @@ static int fsl_ep_enable(struct usb_ep *_ep,
 	unsigned short max = 0;
 	unsigned char mult = 0, zlt;
 	int retval = -EINVAL;
-	unsigned long flags = 0;
+	unsigned long flags;
 
 	ep = container_of(_ep, struct fsl_ep, ep);
 
@@ -631,7 +628,7 @@ static int fsl_ep_disable(struct usb_ep *_ep)
 {
 	struct fsl_udc *udc = NULL;
 	struct fsl_ep *ep = NULL;
-	unsigned long flags = 0;
+	unsigned long flags;
 	u32 epctrl;
 	int ep_num;
 
@@ -1001,7 +998,7 @@ out:	epctrl = fsl_readl(&dr_regs->endptctrl[ep_num]);
 static int fsl_ep_set_halt(struct usb_ep *_ep, int value)
 {
 	struct fsl_ep *ep = NULL;
-	unsigned long flags = 0;
+	unsigned long flags;
 	int status = -EOPNOTSUPP;	/* operation not supported */
 	unsigned char ep_dir = 0, ep_num = 0;
 	struct fsl_udc *udc = NULL;
@@ -1938,7 +1935,7 @@ static int fsl_udc_start(struct usb_gadget *g,
 		struct usb_gadget_driver *driver)
 {
 	int retval = 0;
-	unsigned long flags = 0;
+	unsigned long flags;
 
 	/* lock is needed but whether should use this lock or another */
 	spin_lock_irqsave(&udc_controller->lock, flags);
@@ -2153,7 +2150,6 @@ static int fsl_proc_read(struct seq_file *m, void *v)
 	tmp_reg = fsl_readl(&dr_regs->endpointprime);
 	seq_printf(m, "EP Prime Reg = [0x%x]\n\n", tmp_reg);
 
-#ifndef CONFIG_ARCH_MXC
 	if (udc->pdata->have_sysif_regs) {
 		tmp_reg = usb_sys_regs->snoop1;
 		seq_printf(m, "Snoop1 Reg : = [0x%x]\n\n", tmp_reg);
@@ -2161,7 +2157,6 @@ static int fsl_proc_read(struct seq_file *m, void *v)
 		tmp_reg = usb_sys_regs->control;
 		seq_printf(m, "General Control Reg : = [0x%x]\n\n", tmp_reg);
 	}
-#endif
 
 	/* ------fsl_udc, fsl_ep, fsl_request structure information ----- */
 	ep = &udc->eps[0];
@@ -2412,28 +2407,21 @@ static int fsl_udc_probe(struct platform_device *pdev)
 	 */
 	if (pdata->init && pdata->init(pdev)) {
 		ret = -ENODEV;
-		goto err_iounmap_noclk;
+		goto err_iounmap;
 	}
 
 	/* Set accessors only after pdata->init() ! */
 	fsl_set_accessors(pdata);
 
-#ifndef CONFIG_ARCH_MXC
 	if (pdata->have_sysif_regs)
 		usb_sys_regs = (void *)dr_regs + USB_DR_SYS_OFFSET;
-#endif
-
-	/* Initialize USB clocks */
-	ret = fsl_udc_clk_init(pdev);
-	if (ret < 0)
-		goto err_iounmap_noclk;
 
 	/* Read Device Controller Capability Parameters register */
 	dccparams = fsl_readl(&dr_regs->dccparams);
 	if (!(dccparams & DCCPARAMS_DC)) {
 		ERR("This SOC doesn't support device role\n");
 		ret = -ENODEV;
-		goto err_iounmap;
+		goto err_exit;
 	}
 	/* Get max device endpoints */
 	/* DEN is bidirectional ep number, max_ep doubles the number */
@@ -2442,7 +2430,7 @@ static int fsl_udc_probe(struct platform_device *pdev)
 	ret = platform_get_irq(pdev, 0);
 	if (ret <= 0) {
 		ret = ret ? : -ENODEV;
-		goto err_iounmap;
+		goto err_exit;
 	}
 	udc_controller->irq = ret;
 
@@ -2451,7 +2439,7 @@ static int fsl_udc_probe(struct platform_device *pdev)
 	if (ret != 0) {
 		ERR("cannot request irq %d err %d\n",
 				udc_controller->irq, ret);
-		goto err_iounmap;
+		goto err_exit;
 	}
 
 	/* Initialize the udc structure including QH member and other member */
@@ -2467,10 +2455,6 @@ static int fsl_udc_probe(struct platform_device *pdev)
 		dr_controller_setup(udc_controller);
 	}
 
-	ret = fsl_udc_clk_finalize(pdev);
-	if (ret)
-		goto err_free_irq;
-
 	/* Setup gadget structure */
 	udc_controller->gadget.ops = &fsl_gadget_ops;
 	udc_controller->gadget.max_speed = USB_SPEED_HIGH;
@@ -2530,11 +2514,10 @@ err_del_udc:
 	dma_pool_destroy(udc_controller->td_pool);
 err_free_irq:
 	free_irq(udc_controller->irq, udc_controller);
-err_iounmap:
+err_exit:
 	if (pdata->exit)
 		pdata->exit(pdev);
-	fsl_udc_clk_release();
-err_iounmap_noclk:
+err_iounmap:
 	iounmap(dr_regs);
 err_release_mem_region:
 	if (pdata->operating_mode == FSL_USB2_DR_DEVICE)
@@ -2561,8 +2544,6 @@ static int fsl_udc_remove(struct platform_device *pdev)
 	udc_controller->done = &done;
 	usb_del_gadget_udc(&udc_controller->gadget);
 
-	fsl_udc_clk_release();
-
 	/* DR has been stopped in usb_gadget_unregister_driver() */
 	remove_proc_file();
 
@@ -2677,10 +2658,6 @@ static int fsl_udc_otg_resume(struct device *dev)
 --------------------------------------------------------------------------*/
 static const struct platform_device_id fsl_udc_devtype[] = {
 	{
-		.name = "imx-udc-mx27",
-	}, {
-		.name = "imx-udc-mx51",
-	}, {
 		.name = "fsl-usb2-udc",
 	}, {
 		/* sentinel */
@@ -2689,7 +2666,6 @@ static const struct platform_device_id fsl_udc_devtype[] = {
 MODULE_DEVICE_TABLE(platform, fsl_udc_devtype);
 static struct platform_driver udc_driver = {
 	.remove		= fsl_udc_remove,
-	/* Just for FSL i.mx SoC currently */
 	.id_table	= fsl_udc_devtype,
 	/* these suspend and resume are not usb suspend and resume */
 	.suspend	= fsl_udc_suspend,
diff --git a/drivers/usb/gadget/udc/fsl_usb2_udc.h b/drivers/usb/gadget/udc/fsl_usb2_udc.h
index 4ba651ae9048..2efc5a930b48 100644
--- a/drivers/usb/gadget/udc/fsl_usb2_udc.h
+++ b/drivers/usb/gadget/udc/fsl_usb2_udc.h
@@ -588,23 +588,4 @@ static inline struct ep_queue_head *get_qh_by_ep(struct fsl_ep *ep)
 				USB_DIR_IN) ? 1 : 0];
 }
 
-struct platform_device;
-#ifdef CONFIG_ARCH_MXC
-int fsl_udc_clk_init(struct platform_device *pdev);
-int fsl_udc_clk_finalize(struct platform_device *pdev);
-void fsl_udc_clk_release(void);
-#else
-static inline int fsl_udc_clk_init(struct platform_device *pdev)
-{
-	return 0;
-}
-static inline int fsl_udc_clk_finalize(struct platform_device *pdev)
-{
-	return 0;
-}
-static inline void fsl_udc_clk_release(void)
-{
-}
-#endif
-
 #endif
diff --git a/drivers/usb/gadget/udc/gr_udc.c b/drivers/usb/gadget/udc/gr_udc.c
index f8f3aa52383b..4b35739d3695 100644
--- a/drivers/usb/gadget/udc/gr_udc.c
+++ b/drivers/usb/gadget/udc/gr_udc.c
@@ -207,14 +207,15 @@ DEFINE_SHOW_ATTRIBUTE(gr_dfs);
 static void gr_dfs_create(struct gr_udc *dev)
 {
 	const char *name = "gr_udc_state";
+	struct dentry *root;
 
-	dev->dfs_root = debugfs_create_dir(dev_name(dev->dev), usb_debug_root);
-	debugfs_create_file(name, 0444, dev->dfs_root, dev, &gr_dfs_fops);
+	root = debugfs_create_dir(dev_name(dev->dev), usb_debug_root);
+	debugfs_create_file(name, 0444, root, dev, &gr_dfs_fops);
 }
 
 static void gr_dfs_delete(struct gr_udc *dev)
 {
-	debugfs_remove_recursive(dev->dfs_root);
+	debugfs_remove(debugfs_lookup(dev_name(dev->dev), usb_debug_root));
 }
 
 #else /* !CONFIG_USB_GADGET_DEBUG_FS */
diff --git a/drivers/usb/gadget/udc/gr_udc.h b/drivers/usb/gadget/udc/gr_udc.h
index ac5b3f65adb5..70134239179e 100644
--- a/drivers/usb/gadget/udc/gr_udc.h
+++ b/drivers/usb/gadget/udc/gr_udc.h
@@ -215,8 +215,6 @@ struct gr_udc {
 	struct list_head ep_list;
 
 	spinlock_t lock; /* General lock, a.k.a. "dev->lock" in comments */
-
-	struct dentry *dfs_root;
 };
 
 #define to_gr_udc(gadget)	(container_of((gadget), struct gr_udc, gadget))
diff --git a/drivers/usb/gadget/udc/lpc32xx_udc.c b/drivers/usb/gadget/udc/lpc32xx_udc.c
index 3f1c62adce4b..a25d01c89564 100644
--- a/drivers/usb/gadget/udc/lpc32xx_udc.c
+++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
@@ -127,7 +127,6 @@ struct lpc32xx_udc {
 	struct usb_gadget_driver *driver;
 	struct platform_device	*pdev;
 	struct device		*dev;
-	struct dentry		*pde;
 	spinlock_t		lock;
 	struct i2c_client	*isp1301_i2c_client;
 
@@ -528,12 +527,12 @@ DEFINE_SHOW_ATTRIBUTE(udc);
 
 static void create_debug_file(struct lpc32xx_udc *udc)
 {
-	udc->pde = debugfs_create_file(debug_filename, 0, NULL, udc, &udc_fops);
+	debugfs_create_file(debug_filename, 0, NULL, udc, &udc_fops);
 }
 
 static void remove_debug_file(struct lpc32xx_udc *udc)
 {
-	debugfs_remove(udc->pde);
+	debugfs_remove(debugfs_lookup(debug_filename, NULL));
 }
 
 #else
diff --git a/drivers/usb/gadget/udc/mv_u3d_core.c b/drivers/usb/gadget/udc/mv_u3d_core.c
index 5486f5a70868..ce3d7a3eb7e3 100644
--- a/drivers/usb/gadget/udc/mv_u3d_core.c
+++ b/drivers/usb/gadget/udc/mv_u3d_core.c
@@ -941,7 +941,7 @@ mv_u3d_ep_set_stall(struct mv_u3d *u3d, u8 ep_num, u8 direction, int stall)
 static int mv_u3d_ep_set_halt_wedge(struct usb_ep *_ep, int halt, int wedge)
 {
 	struct mv_u3d_ep *ep;
-	unsigned long flags = 0;
+	unsigned long flags;
 	int status = 0;
 	struct mv_u3d *u3d;
 
diff --git a/drivers/usb/gadget/udc/mv_udc_core.c b/drivers/usb/gadget/udc/mv_udc_core.c
index 0fb4ef464321..7f24ce400b59 100644
--- a/drivers/usb/gadget/udc/mv_udc_core.c
+++ b/drivers/usb/gadget/udc/mv_udc_core.c
@@ -888,7 +888,7 @@ static int ep_is_stall(struct mv_udc *udc, u8 ep_num, u8 direction)
 static int mv_ep_set_halt_wedge(struct usb_ep *_ep, int halt, int wedge)
 {
 	struct mv_ep *ep;
-	unsigned long flags = 0;
+	unsigned long flags;
 	int status = 0;
 	struct mv_udc *udc;
 
diff --git a/drivers/usb/gadget/udc/net2272.c b/drivers/usb/gadget/udc/net2272.c
index 89f479b78d80..7c38057dcb4a 100644
--- a/drivers/usb/gadget/udc/net2272.c
+++ b/drivers/usb/gadget/udc/net2272.c
@@ -1150,6 +1150,7 @@ net2272_pullup(struct usb_gadget *_gadget, int is_on)
 static int net2272_start(struct usb_gadget *_gadget,
 		struct usb_gadget_driver *driver);
 static int net2272_stop(struct usb_gadget *_gadget);
+static void net2272_async_callbacks(struct usb_gadget *_gadget, bool enable);
 
 static const struct usb_gadget_ops net2272_ops = {
 	.get_frame	= net2272_get_frame,
@@ -1158,6 +1159,7 @@ static const struct usb_gadget_ops net2272_ops = {
 	.pullup		= net2272_pullup,
 	.udc_start	= net2272_start,
 	.udc_stop	= net2272_stop,
+	.udc_async_callbacks = net2272_async_callbacks,
 };
 
 /*---------------------------------------------------------------------------*/
@@ -1476,7 +1478,7 @@ stop_activity(struct net2272 *dev, struct usb_gadget_driver *driver)
 		net2272_dequeue_all(&dev->ep[i]);
 
 	/* report disconnect; the driver is already quiesced */
-	if (driver) {
+	if (dev->async_callbacks && driver) {
 		spin_unlock(&dev->lock);
 		driver->disconnect(&dev->gadget);
 		spin_lock(&dev->lock);
@@ -1501,6 +1503,15 @@ static int net2272_stop(struct usb_gadget *_gadget)
 	return 0;
 }
 
+static void net2272_async_callbacks(struct usb_gadget *_gadget, bool enable)
+{
+	struct net2272	*dev = container_of(_gadget, struct net2272, gadget);
+
+	spin_lock_irq(&dev->lock);
+	dev->async_callbacks = enable;
+	spin_unlock_irq(&dev->lock);
+}
+
 /*---------------------------------------------------------------------------*/
 /* handle ep-a/ep-b dma completions */
 static void
@@ -1910,9 +1921,11 @@ net2272_handle_stat0_irqs(struct net2272 *dev, u8 stat)
 				u.r.bRequestType, u.r.bRequest,
 				u.r.wValue, u.r.wIndex,
 				net2272_ep_read(ep, EP_CFG));
-			spin_unlock(&dev->lock);
-			tmp = dev->driver->setup(&dev->gadget, &u.r);
-			spin_lock(&dev->lock);
+			if (dev->async_callbacks) {
+				spin_unlock(&dev->lock);
+				tmp = dev->driver->setup(&dev->gadget, &u.r);
+				spin_lock(&dev->lock);
+			}
 		}
 
 		/* stall ep0 on error */
@@ -1994,14 +2007,14 @@ net2272_handle_stat1_irqs(struct net2272 *dev, u8 stat)
 			if (disconnect || reset) {
 				stop_activity(dev, dev->driver);
 				net2272_ep0_start(dev);
-				spin_unlock(&dev->lock);
-				if (reset)
-					usb_gadget_udc_reset
-						(&dev->gadget, dev->driver);
-				else
-					(dev->driver->disconnect)
-						(&dev->gadget);
-				spin_lock(&dev->lock);
+				if (dev->async_callbacks) {
+					spin_unlock(&dev->lock);
+					if (reset)
+						usb_gadget_udc_reset(&dev->gadget, dev->driver);
+					else
+						(dev->driver->disconnect)(&dev->gadget);
+					spin_lock(&dev->lock);
+				}
 				return;
 			}
 		}
@@ -2015,14 +2028,14 @@ net2272_handle_stat1_irqs(struct net2272 *dev, u8 stat)
 	if (stat & tmp) {
 		net2272_write(dev, IRQSTAT1, tmp);
 		if (stat & (1 << SUSPEND_REQUEST_INTERRUPT)) {
-			if (dev->driver->suspend)
+			if (dev->async_callbacks && dev->driver->suspend)
 				dev->driver->suspend(&dev->gadget);
 			if (!enable_suspend) {
 				stat &= ~(1 << SUSPEND_REQUEST_INTERRUPT);
 				dev_dbg(dev->dev, "Suspend disabled, ignoring\n");
 			}
 		} else {
-			if (dev->driver->resume)
+			if (dev->async_callbacks && dev->driver->resume)
 				dev->driver->resume(&dev->gadget);
 		}
 		stat &= ~tmp;
diff --git a/drivers/usb/gadget/udc/net2272.h b/drivers/usb/gadget/udc/net2272.h
index c669308111c2..a9994f737588 100644
--- a/drivers/usb/gadget/udc/net2272.h
+++ b/drivers/usb/gadget/udc/net2272.h
@@ -442,6 +442,7 @@ struct net2272 {
 	         softconnect:1,
 	         wakeup:1,
 		 added:1,
+		 async_callbacks:1,
 	         dma_eot_polarity:1,
 	         dma_dack_polarity:1,
 	         dma_dreq_polarity:1,
diff --git a/drivers/usb/gadget/udc/net2280.c b/drivers/usb/gadget/udc/net2280.c
index fc9f99fe7f37..16e7d2db6411 100644
--- a/drivers/usb/gadget/udc/net2280.c
+++ b/drivers/usb/gadget/udc/net2280.c
@@ -1617,6 +1617,7 @@ static struct usb_ep *net2280_match_ep(struct usb_gadget *_gadget,
 static int net2280_start(struct usb_gadget *_gadget,
 		struct usb_gadget_driver *driver);
 static int net2280_stop(struct usb_gadget *_gadget);
+static void net2280_async_callbacks(struct usb_gadget *_gadget, bool enable);
 
 static const struct usb_gadget_ops net2280_ops = {
 	.get_frame	= net2280_get_frame,
@@ -1625,6 +1626,7 @@ static const struct usb_gadget_ops net2280_ops = {
 	.pullup		= net2280_pullup,
 	.udc_start	= net2280_start,
 	.udc_stop	= net2280_stop,
+	.udc_async_callbacks = net2280_async_callbacks,
 	.match_ep	= net2280_match_ep,
 };
 
@@ -2472,7 +2474,7 @@ static void stop_activity(struct net2280 *dev, struct usb_gadget_driver *driver)
 		nuke(&dev->ep[i]);
 
 	/* report disconnect; the driver is already quiesced */
-	if (driver) {
+	if (dev->async_callbacks && driver) {
 		spin_unlock(&dev->lock);
 		driver->disconnect(&dev->gadget);
 		spin_lock(&dev->lock);
@@ -2502,6 +2504,15 @@ static int net2280_stop(struct usb_gadget *_gadget)
 	return 0;
 }
 
+static void net2280_async_callbacks(struct usb_gadget *_gadget, bool enable)
+{
+	struct net2280	*dev = container_of(_gadget, struct net2280, gadget);
+
+	spin_lock_irq(&dev->lock);
+	dev->async_callbacks = enable;
+	spin_unlock_irq(&dev->lock);
+}
+
 /*-------------------------------------------------------------------------*/
 
 /* handle ep0, ep-e, ep-f with 64 byte packets: packet per irq.
@@ -2814,8 +2825,6 @@ static void defect7374_workaround(struct net2280 *dev, struct usb_ctrlrequest r)
 		 * - Wait and try again.
 		 */
 		udelay(DEFECT_7374_PROCESSOR_WAIT_TIME);
-
-		continue;
 	}
 
 
@@ -3042,9 +3051,11 @@ usb3_delegate:
 				readl(&ep->cfg->ep_cfg));
 
 		ep->responded = 0;
-		spin_unlock(&dev->lock);
-		tmp = dev->driver->setup(&dev->gadget, &r);
-		spin_lock(&dev->lock);
+		if (dev->async_callbacks) {
+			spin_unlock(&dev->lock);
+			tmp = dev->driver->setup(&dev->gadget, &r);
+			spin_lock(&dev->lock);
+		}
 	}
 do_stall3:
 	if (tmp < 0) {
@@ -3284,9 +3295,11 @@ delegate:
 				w_value, w_index, w_length,
 				readl(&ep->cfg->ep_cfg));
 			ep->responded = 0;
-			spin_unlock(&dev->lock);
-			tmp = dev->driver->setup(&dev->gadget, &u.r);
-			spin_lock(&dev->lock);
+			if (dev->async_callbacks) {
+				spin_unlock(&dev->lock);
+				tmp = dev->driver->setup(&dev->gadget, &u.r);
+				spin_lock(&dev->lock);
+			}
 		}
 
 		/* stall ep0 on error */
@@ -3391,14 +3404,14 @@ __acquires(dev->lock)
 			if (disconnect || reset) {
 				stop_activity(dev, dev->driver);
 				ep0_start(dev);
-				spin_unlock(&dev->lock);
-				if (reset)
-					usb_gadget_udc_reset
-						(&dev->gadget, dev->driver);
-				else
-					(dev->driver->disconnect)
-						(&dev->gadget);
-				spin_lock(&dev->lock);
+				if (dev->async_callbacks) {
+					spin_unlock(&dev->lock);
+					if (reset)
+						usb_gadget_udc_reset(&dev->gadget, dev->driver);
+					else
+						(dev->driver->disconnect)(&dev->gadget);
+					spin_lock(&dev->lock);
+				}
 				return;
 			}
 		}
@@ -3419,12 +3432,12 @@ __acquires(dev->lock)
 		writel(tmp, &dev->regs->irqstat1);
 		spin_unlock(&dev->lock);
 		if (stat & BIT(SUSPEND_REQUEST_INTERRUPT)) {
-			if (dev->driver->suspend)
+			if (dev->async_callbacks && dev->driver->suspend)
 				dev->driver->suspend(&dev->gadget);
 			if (!enable_suspend)
 				stat &= ~BIT(SUSPEND_REQUEST_INTERRUPT);
 		} else {
-			if (dev->driver->resume)
+			if (dev->async_callbacks && dev->driver->resume)
 				dev->driver->resume(&dev->gadget);
 			/* at high speed, note erratum 0133 */
 		}
diff --git a/drivers/usb/gadget/udc/net2280.h b/drivers/usb/gadget/udc/net2280.h
index 7da3dc1e9729..34716a9f4926 100644
--- a/drivers/usb/gadget/udc/net2280.h
+++ b/drivers/usb/gadget/udc/net2280.h
@@ -162,6 +162,7 @@ struct net2280 {
 					ltm_enable:1,
 					wakeup_enable:1,
 					addressed_state:1,
+					async_callbacks:1,
 					bug7734_patched:1;
 	u16				chiprev;
 	int enhanced_mode;
diff --git a/drivers/usb/gadget/udc/pxa25x_udc.c b/drivers/usb/gadget/udc/pxa25x_udc.c
index 10324a7334fe..69ef1e669d0c 100644
--- a/drivers/usb/gadget/udc/pxa25x_udc.c
+++ b/drivers/usb/gadget/udc/pxa25x_udc.c
@@ -1338,10 +1338,10 @@ DEFINE_SHOW_ATTRIBUTE(udc_debug);
 
 #define create_debug_files(dev) \
 	do { \
-		dev->debugfs_udc = debugfs_create_file(dev->gadget.name, \
+		debugfs_create_file(dev->gadget.name, \
 			S_IRUGO, NULL, dev, &udc_debug_fops); \
 	} while (0)
-#define remove_debug_files(dev) debugfs_remove(dev->debugfs_udc)
+#define remove_debug_files(dev) debugfs_remove(debugfs_lookup(dev->gadget.name, NULL))
 
 #else	/* !CONFIG_USB_GADGET_DEBUG_FILES */
 
diff --git a/drivers/usb/gadget/udc/pxa25x_udc.h b/drivers/usb/gadget/udc/pxa25x_udc.h
index ccc6b921f067..aa4b68fd9fc0 100644
--- a/drivers/usb/gadget/udc/pxa25x_udc.h
+++ b/drivers/usb/gadget/udc/pxa25x_udc.h
@@ -116,10 +116,6 @@ struct pxa25x_udc {
 	struct usb_phy				*transceiver;
 	u64					dma_mask;
 	struct pxa25x_ep			ep [PXA_UDC_NUM_ENDPOINTS];
-
-#ifdef CONFIG_USB_GADGET_DEBUG_FS
-	struct dentry				*debugfs_udc;
-#endif
 	void __iomem				*regs;
 };
 #define to_pxa25x(g)	(container_of((g), struct pxa25x_udc, gadget))
diff --git a/drivers/usb/gadget/udc/pxa27x_udc.c b/drivers/usb/gadget/udc/pxa27x_udc.c
index ce57961dfd2d..f4b7a2a3e711 100644
--- a/drivers/usb/gadget/udc/pxa27x_udc.c
+++ b/drivers/usb/gadget/udc/pxa27x_udc.c
@@ -208,8 +208,6 @@ static void pxa_init_debugfs(struct pxa_udc *udc)
 	struct dentry *root;
 
 	root = debugfs_create_dir(udc->gadget.name, usb_debug_root);
-	udc->debugfs_root = root;
-
 	debugfs_create_file("udcstate", 0400, root, udc, &state_dbg_fops);
 	debugfs_create_file("queues", 0400, root, udc, &queues_dbg_fops);
 	debugfs_create_file("epstate", 0400, root, udc, &eps_dbg_fops);
@@ -217,7 +215,7 @@ static void pxa_init_debugfs(struct pxa_udc *udc)
 
 static void pxa_cleanup_debugfs(struct pxa_udc *udc)
 {
-	debugfs_remove_recursive(udc->debugfs_root);
+	debugfs_remove(debugfs_lookup(udc->gadget.name, usb_debug_root));
 }
 
 #else
@@ -1730,7 +1728,7 @@ static void udc_enable(struct pxa_udc *udc)
 }
 
 /**
- * pxa27x_start - Register gadget driver
+ * pxa27x_udc_start - Register gadget driver
  * @g: gadget
  * @driver: gadget driver
  *
diff --git a/drivers/usb/gadget/udc/pxa27x_udc.h b/drivers/usb/gadget/udc/pxa27x_udc.h
index 13b2977399ab..0a6bc18a1264 100644
--- a/drivers/usb/gadget/udc/pxa27x_udc.h
+++ b/drivers/usb/gadget/udc/pxa27x_udc.h
@@ -440,7 +440,6 @@ struct udc_stats {
  * @last_interface: UDC interface of the last SET_INTERFACE host request
  * @last_alternate: UDC altsetting of the last SET_INTERFACE host request
  * @udccsr0: save of udccsr0 in case of suspend
- * @debugfs_root: root entry of debug filesystem
  * @debugfs_state: debugfs entry for "udcstate"
  * @debugfs_queues: debugfs entry for "queues"
  * @debugfs_eps: debugfs entry for "epstate"
@@ -474,9 +473,6 @@ struct pxa_udc {
 #ifdef CONFIG_PM
 	unsigned				udccsr0;
 #endif
-#ifdef CONFIG_USB_GADGET_DEBUG_FS
-	struct dentry				*debugfs_root;
-#endif
 };
 #define to_pxa(g)	(container_of((g), struct pxa_udc, gadget))
 
diff --git a/drivers/usb/gadget/udc/s3c-hsudc.c b/drivers/usb/gadget/udc/s3c-hsudc.c
index 7bd5182ce3ef..89f1f8c9f02e 100644
--- a/drivers/usb/gadget/udc/s3c-hsudc.c
+++ b/drivers/usb/gadget/udc/s3c-hsudc.c
@@ -1220,9 +1220,8 @@ static int s3c_hsudc_probe(struct platform_device *pdev)
 	struct s3c24xx_hsudc_platdata *pd = dev_get_platdata(&pdev->dev);
 	int ret, i;
 
-	hsudc = devm_kzalloc(&pdev->dev, sizeof(struct s3c_hsudc) +
-			sizeof(struct s3c_hsudc_ep) * pd->epnum,
-			GFP_KERNEL);
+	hsudc = devm_kzalloc(&pdev->dev, struct_size(hsudc, ep, pd->epnum),
+			     GFP_KERNEL);
 	if (!hsudc)
 		return -ENOMEM;
 
diff --git a/drivers/usb/gadget/udc/s3c2410_udc.c b/drivers/usb/gadget/udc/s3c2410_udc.c
index b154b62abefa..179777cb699f 100644
--- a/drivers/usb/gadget/udc/s3c2410_udc.c
+++ b/drivers/usb/gadget/udc/s3c2410_udc.c
@@ -198,7 +198,7 @@ static inline void s3c2410_udc_set_ep0_de(void __iomem *base)
 	udc_writeb(base, S3C2410_UDC_EP0_CSR_DE, S3C2410_UDC_EP0_CSR_REG);
 }
 
-inline void s3c2410_udc_set_ep0_ss(void __iomem *b)
+static inline void s3c2410_udc_set_ep0_ss(void __iomem *b)
 {
 	udc_writeb(b, S3C2410_UDC_INDEX_EP0, S3C2410_UDC_INDEX_REG);
 	udc_writeb(b, S3C2410_UDC_EP0_CSR_SENDSTL, S3C2410_UDC_EP0_CSR_REG);
@@ -1843,9 +1843,8 @@ static int s3c2410_udc_probe(struct platform_device *pdev)
 	if (retval)
 		goto err_add_udc;
 
-	udc->regs_info = debugfs_create_file("registers", S_IRUGO,
-					     s3c2410_udc_debugfs_root, udc,
-					     &s3c2410_udc_debugfs_fops);
+	debugfs_create_file("registers", S_IRUGO, s3c2410_udc_debugfs_root, udc,
+			    &s3c2410_udc_debugfs_fops);
 
 	dev_dbg(dev, "probe ok\n");
 
@@ -1889,7 +1888,7 @@ static int s3c2410_udc_remove(struct platform_device *pdev)
 		return -EBUSY;
 
 	usb_del_gadget_udc(&udc->gadget);
-	debugfs_remove(udc->regs_info);
+	debugfs_remove(debugfs_lookup("registers", s3c2410_udc_debugfs_root));
 
 	if (udc_info && !udc_info->udc_command &&
 		gpio_is_valid(udc_info->pullup_pin))
diff --git a/drivers/usb/gadget/udc/s3c2410_udc.h b/drivers/usb/gadget/udc/s3c2410_udc.h
index 68bdf3e5aac2..135a5bff3c74 100644
--- a/drivers/usb/gadget/udc/s3c2410_udc.h
+++ b/drivers/usb/gadget/udc/s3c2410_udc.h
@@ -89,7 +89,6 @@ struct s3c2410_udc {
 	unsigned			req_config : 1;
 	unsigned			req_pending : 1;
 	u8				vbus;
-	struct dentry			*regs_info;
 	int				irq;
 };
 #define to_s3c2410(g)	(container_of((g), struct s3c2410_udc, gadget))
diff --git a/drivers/usb/gadget/udc/tegra-xudc.c b/drivers/usb/gadget/udc/tegra-xudc.c
index 2319c9737c2b..a54d1cef17db 100644
--- a/drivers/usb/gadget/udc/tegra-xudc.c
+++ b/drivers/usb/gadget/udc/tegra-xudc.c
@@ -1907,7 +1907,7 @@ static void tegra_xudc_ep_free_request(struct usb_ep *usb_ep,
 	kfree(req);
 }
 
-static struct usb_ep_ops tegra_xudc_ep_ops = {
+static const struct usb_ep_ops tegra_xudc_ep_ops = {
 	.enable = tegra_xudc_ep_enable,
 	.disable = tegra_xudc_ep_disable,
 	.alloc_request = tegra_xudc_ep_alloc_request,
@@ -1928,7 +1928,7 @@ static int tegra_xudc_ep0_disable(struct usb_ep *usb_ep)
 	return -EBUSY;
 }
 
-static struct usb_ep_ops tegra_xudc_ep0_ops = {
+static const struct usb_ep_ops tegra_xudc_ep0_ops = {
 	.enable = tegra_xudc_ep0_enable,
 	.disable = tegra_xudc_ep0_disable,
 	.alloc_request = tegra_xudc_ep_alloc_request,
@@ -2168,7 +2168,7 @@ static int tegra_xudc_set_selfpowered(struct usb_gadget *gadget, int is_on)
 	return 0;
 }
 
-static struct usb_gadget_ops tegra_xudc_gadget_ops = {
+static const struct usb_gadget_ops tegra_xudc_gadget_ops = {
 	.get_frame = tegra_xudc_gadget_get_frame,
 	.wakeup = tegra_xudc_gadget_wakeup,
 	.pullup = tegra_xudc_gadget_pullup,
@@ -3508,10 +3508,8 @@ static int tegra_xudc_phy_get(struct tegra_xudc *xudc)
 		xudc->utmi_phy[i] = devm_phy_optional_get(xudc->dev, phy_name);
 		if (IS_ERR(xudc->utmi_phy[i])) {
 			err = PTR_ERR(xudc->utmi_phy[i]);
-			if (err != -EPROBE_DEFER)
-				dev_err(xudc->dev, "failed to get usb2-%d PHY: %d\n",
-					i, err);
-
+			dev_err_probe(xudc->dev, err,
+				      "failed to get usb2-%d PHY\n", i);
 			goto clean_up;
 		} else if (xudc->utmi_phy[i]) {
 			/* Get usb-phy, if utmi phy is available */
@@ -3520,8 +3518,8 @@ static int tegra_xudc_phy_get(struct tegra_xudc *xudc)
 						&xudc->vbus_nb);
 			if (IS_ERR(xudc->usbphy[i])) {
 				err = PTR_ERR(xudc->usbphy[i]);
-				dev_err(xudc->dev, "failed to get usbphy-%d: %d\n",
-					i, err);
+				dev_err_probe(xudc->dev, err,
+					      "failed to get usbphy-%d\n", i);
 				goto clean_up;
 			}
 		} else if (!xudc->utmi_phy[i]) {
@@ -3538,10 +3536,8 @@ static int tegra_xudc_phy_get(struct tegra_xudc *xudc)
 		xudc->usb3_phy[i] = devm_phy_optional_get(xudc->dev, phy_name);
 		if (IS_ERR(xudc->usb3_phy[i])) {
 			err = PTR_ERR(xudc->usb3_phy[i]);
-			if (err != -EPROBE_DEFER)
-				dev_err(xudc->dev, "failed to get usb3-%d PHY: %d\n",
-					usb3, err);
-
+			dev_err_probe(xudc->dev, err,
+				      "failed to get usb3-%d PHY\n", usb3);
 			goto clean_up;
 		} else if (xudc->usb3_phy[i])
 			dev_dbg(xudc->dev, "usb3-%d PHY registered", usb3);
@@ -3781,9 +3777,7 @@ static int tegra_xudc_probe(struct platform_device *pdev)
 
 	err = devm_clk_bulk_get(&pdev->dev, xudc->soc->num_clks, xudc->clks);
 	if (err) {
-		if (err != -EPROBE_DEFER)
-			dev_err(xudc->dev, "failed to request clocks: %d\n", err);
-
+		dev_err_probe(xudc->dev, err, "failed to request clocks\n");
 		return err;
 	}
 
@@ -3798,9 +3792,7 @@ static int tegra_xudc_probe(struct platform_device *pdev)
 	err = devm_regulator_bulk_get(&pdev->dev, xudc->soc->num_supplies,
 				      xudc->supplies);
 	if (err) {
-		if (err != -EPROBE_DEFER)
-			dev_err(xudc->dev, "failed to request regulators: %d\n", err);
-
+		dev_err_probe(xudc->dev, err, "failed to request regulators\n");
 		return err;
 	}
 
diff --git a/drivers/usb/gadget/udc/trace.c b/drivers/usb/gadget/udc/trace.c
index 7430624c0bd7..19e837de2a20 100644
--- a/drivers/usb/gadget/udc/trace.c
+++ b/drivers/usb/gadget/udc/trace.c
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
-/**
+/*
  * trace.c - USB Gadget Framework Trace Support
  *
  * Copyright (C) 2016 Intel Corporation
diff --git a/drivers/usb/gadget/udc/trace.h b/drivers/usb/gadget/udc/trace.h
index 2d1f68b5ea76..98584f6b6c66 100644
--- a/drivers/usb/gadget/udc/trace.h
+++ b/drivers/usb/gadget/udc/trace.h
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
-/**
+/*
  * udc.c - Core UDC Framework
  *
  * Copyright (C) 2016 Intel Corporation
diff --git a/drivers/usb/gadget/udc/udc-xilinx.c b/drivers/usb/gadget/udc/udc-xilinx.c
index 72f2ea062d55..fb4ffedd6f0d 100644
--- a/drivers/usb/gadget/udc/udc-xilinx.c
+++ b/drivers/usb/gadget/udc/udc-xilinx.c
@@ -791,7 +791,7 @@ static int xudc_ep_set_halt(struct usb_ep *_ep, int value)
 }
 
 /**
- * xudc_ep_enable - Enables the given endpoint.
+ * __xudc_ep_enable - Enables the given endpoint.
  * @ep: pointer to the xusb endpoint structure.
  * @desc: pointer to usb endpoint descriptor.
  *
@@ -987,7 +987,7 @@ static void xudc_free_request(struct usb_ep *_ep, struct usb_request *_req)
 }
 
 /**
- * xudc_ep0_queue - Adds the request to endpoint 0 queue.
+ * __xudc_ep0_queue - Adds the request to endpoint 0 queue.
  * @ep0: pointer to the xusb endpoint 0 structure.
  * @req: pointer to the xusb request structure.
  *