clk_enable() may fail according to the API contract.
Previously, udc_enable() ignored its return value and returned void.

Modify udc_enable() to return the error code. Additionally, update
all of its callers (pxa_udc_pullup, pxa_udc_vbus_session,
pxa27x_udc_start, pxa_udc_probe, and pxa_udc_resume) to check
this return value and handle the failure properly with necessary
cleanups or rollbacks.

Signed-off-by: Zhaoyang Yu <2426767509@qq.com>
---
Changes in v5:
- Rewrote the commit message in the imperative mood and updated it to
  accurately reflect the error handling/rollback changes (Markus Elfring).

Changes in v4:
- Added missing state rollbacks in pxa_udc_pullup(), pxa_udc_vbus_session(),
  and pxa_udc_resume() when udc_enable() fails, per Greg KH's review.

Changes in v3:
- Changed udc_enable() return type from void to int.
- Propagated the error to all caller functions and added proper
  error handling/rollback per Greg KH's review.

Changes in v2:
- Fixed a formatting issue by moving the 'int ret' declaration to
  the beginning of the function block.

 drivers/usb/gadget/udc/pxa27x_udc.c | 66 +++++++++++++++++++++++------
 1 file changed, 52 insertions(+), 14 deletions(-)

diff --git a/drivers/usb/gadget/udc/pxa27x_udc.c b/drivers/usb/gadget/udc/pxa27x_udc.c
index 897f53601b5b..348af4d29c4d 100644
--- a/drivers/usb/gadget/udc/pxa27x_udc.c
+++ b/drivers/usb/gadget/udc/pxa27x_udc.c
@@ -1462,7 +1462,7 @@ static int pxa_udc_wakeup(struct usb_gadget *_gadget)
 	return 0;
 }
 
-static void udc_enable(struct pxa_udc *udc);
+static int udc_enable(struct pxa_udc *udc);
 static void udc_disable(struct pxa_udc *udc);
 
 /**
@@ -1519,14 +1519,20 @@ static int should_disable_udc(struct pxa_udc *udc)
 static int pxa_udc_pullup(struct usb_gadget *_gadget, int is_active)
 {
 	struct pxa_udc *udc = to_gadget_udc(_gadget);
+	int ret;
 
 	if (!udc->gpiod && !udc->udc_command)
 		return -EOPNOTSUPP;
 
 	dplus_pullup(udc, is_active);
 
-	if (should_enable_udc(udc))
-		udc_enable(udc);
+	if (should_enable_udc(udc)) {
+		ret = udc_enable(udc);
+		if (ret) {
+			dplus_pullup(udc, !is_active);
+			return ret;
+		}
+	}
 	if (should_disable_udc(udc))
 		udc_disable(udc);
 	return 0;
@@ -1545,10 +1551,16 @@ static int pxa_udc_pullup(struct usb_gadget *_gadget, int is_active)
 static int pxa_udc_vbus_session(struct usb_gadget *_gadget, int is_active)
 {
 	struct pxa_udc *udc = to_gadget_udc(_gadget);
+	int ret;
 
 	udc->vbus_sensed = is_active;
-	if (should_enable_udc(udc))
-		udc_enable(udc);
+	if (should_enable_udc(udc)) {
+		ret = udc_enable(udc);
+		if (ret) {
+			udc->vbus_sensed = !is_active;
+			return ret;
+		}
+	}
 	if (should_disable_udc(udc))
 		udc_disable(udc);
 
@@ -1691,12 +1703,18 @@ static void udc_init_data(struct pxa_udc *dev)
  * Enables the udc device : enables clocks, udc interrupts, control endpoint
  * interrupts, sets usb as UDC client and setups endpoints.
  */
-static void udc_enable(struct pxa_udc *udc)
+static int udc_enable(struct pxa_udc *udc)
 {
+	int ret;
+
 	if (udc->enabled)
-		return;
+		return 0;
 
-	clk_enable(udc->clk);
+	ret = clk_enable(udc->clk);
+	if (ret) {
+		dev_err(udc->dev, "clk_enable failed: %d\n", ret);
+		return ret;
+	}
 	udc_writel(udc, UDCICR0, 0);
 	udc_writel(udc, UDCICR1, 0);
 	udc_clear_mask_UDCCR(udc, UDCCR_UDE);
@@ -1726,6 +1744,8 @@ static void udc_enable(struct pxa_udc *udc)
 	pio_irq_enable(&udc->pxa_ep[0]);
 
 	udc->enabled = 1;
+
+	return 0;
 }
 
 /**
@@ -1761,10 +1781,16 @@ static int pxa27x_udc_start(struct usb_gadget *g,
 		}
 	}
 
-	if (should_enable_udc(udc))
-		udc_enable(udc);
+	if (should_enable_udc(udc)) {
+		retval = udc_enable(udc);
+		if (retval)
+			goto fail_enable;
+	}
 	return 0;
 
+fail_enable:
+	if (!IS_ERR_OR_NULL(udc->transceiver))
+		otg_set_peripheral(udc->transceiver->otg, NULL);
 fail:
 	udc->driver = NULL;
 	return retval;
@@ -2430,10 +2456,16 @@ static int pxa_udc_probe(struct platform_device *pdev)
 		goto err_add_gadget;
 
 	pxa_init_debugfs(udc);
-	if (should_enable_udc(udc))
-		udc_enable(udc);
+	if (should_enable_udc(udc)) {
+		retval = udc_enable(udc);
+		if (retval)
+			goto err_enable;
+	}
 	return 0;
 
+err_enable:
+	usb_del_gadget_udc(&udc->gadget);
+	pxa_cleanup_debugfs(udc);
 err_add_gadget:
 	if (!IS_ERR_OR_NULL(udc->transceiver))
 		usb_unregister_notifier(udc->transceiver, &pxa27x_udc_phy);
@@ -2509,13 +2541,19 @@ static int pxa_udc_resume(struct platform_device *_dev)
 {
 	struct pxa_udc *udc = platform_get_drvdata(_dev);
 	struct pxa_ep *ep;
+	int ret;
 
 	ep = &udc->pxa_ep[0];
 	udc_ep_writel(ep, UDCCSR, udc->udccsr0 & (UDCCSR0_FST | UDCCSR0_DME));
 
 	dplus_pullup(udc, udc->pullup_resume);
-	if (should_enable_udc(udc))
-		udc_enable(udc);
+	if (should_enable_udc(udc)) {
+		ret = udc_enable(udc);
+		if (ret) {
+			dplus_pullup(udc, !udc->pullup_resume);
+			return ret;
+		}
+	}
 	/*
 	 * We do not handle OTG yet.
 	 *
-- 
2.34.1