[PATCH v3] usb: dwc3: Abort suspend on soft disconnect failure

[Kuen-Han Tsai]

When dwc3_gadget_soft_disconnect() fails, dwc3_suspend_common() keeps
going with the suspend, resulting in a period where the power domain is
off, but the gadget driver remains connected.  Within this time frame,
invoking vbus_event_work() will cause an error as it attempts to access
DWC3 registers for endpoint disabling after the power domain has been
completely shut down.

Abort the suspend sequence when dwc3_gadget_suspend() cannot halt the
controller and proceeds with a soft connect.

Fixes: 9f8a67b65a49 ("usb: dwc3: gadget: fix gadget suspend/resume")
CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Kuen-Han Tsai <khtsai@xxxxxxxxxx>
---

Kernel panic - not syncing: Asynchronous SError Interrupt
Workqueue: events vbus_event_work
Call trace:
 dump_backtrace+0xf4/0x118
 show_stack+0x18/0x24
 dump_stack_lvl+0x60/0x7c
 dump_stack+0x18/0x3c
 panic+0x16c/0x390
 nmi_panic+0xa4/0xa8
 arm64_serror_panic+0x6c/0x94
 do_serror+0xc4/0xd0
 el1h_64_error_handler+0x34/0x48
 el1h_64_error+0x68/0x6c
 readl+0x4c/0x8c
 __dwc3_gadget_ep_disable+0x48/0x230
 dwc3_gadget_ep_disable+0x50/0xc0
 usb_ep_disable+0x44/0xe4
 ffs_func_eps_disable+0x64/0xc8
 ffs_func_set_alt+0x74/0x368
 ffs_func_disable+0x18/0x28
 composite_disconnect+0x90/0xec
 configfs_composite_disconnect+0x64/0x88
 usb_gadget_disconnect_locked+0xc0/0x168
 vbus_event_work+0x3c/0x58
 process_one_work+0x1e4/0x43c
 worker_thread+0x25c/0x430
 kthread+0x104/0x1d4
 ret_from_fork+0x10/0x20

---
Changelog:

v3:
- change the Fixes tag

v2:
- move declarations in separate lines
- add the Fixes tag

---
 drivers/usb/dwc3/core.c   |  9 +++++++--
 drivers/usb/dwc3/gadget.c | 22 +++++++++-------------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 66a08b527165..1cf1996ae1fb 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -2388,6 +2388,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 {
 	u32 reg;
 	int i;
+	int ret;

 	if (!pm_runtime_suspended(dwc->dev) && !PMSG_IS_AUTO(msg)) {
 		dwc->susphy_state = (dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
@@ -2406,7 +2407,9 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 	case DWC3_GCTL_PRTCAP_DEVICE:
 		if (pm_runtime_suspended(dwc->dev))
 			break;
-		dwc3_gadget_suspend(dwc);
+		ret = dwc3_gadget_suspend(dwc);
+		if (ret)
+			return ret
 		synchronize_irq(dwc->irq_gadget);
 		dwc3_core_exit(dwc);
 		break;
@@ -2441,7 +2444,9 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 			break;

 		if (dwc->current_otg_role == DWC3_OTG_ROLE_DEVICE) {
-			dwc3_gadget_suspend(dwc);
+			ret = dwc3_gadget_suspend(dwc);
+			if (ret)
+				return ret;
 			synchronize_irq(dwc->irq_gadget);
 		}

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 89a4dc8ebf94..316c1589618e 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -4776,26 +4776,22 @@ int dwc3_gadget_suspend(struct dwc3 *dwc)
 	int ret;

 	ret = dwc3_gadget_soft_disconnect(dwc);
-	if (ret)
-		goto err;
-
-	spin_lock_irqsave(&dwc->lock, flags);
-	if (dwc->gadget_driver)
-		dwc3_disconnect_gadget(dwc);
-	spin_unlock_irqrestore(&dwc->lock, flags);
-
-	return 0;
-
-err:
 	/*
 	 * Attempt to reset the controller's state. Likely no
 	 * communication can be established until the host
 	 * performs a port reset.
 	 */
-	if (dwc->softconnect)
+	if (ret && dwc->softconnect) {
 		dwc3_gadget_soft_connect(dwc);
+		return ret;
+	}

-	return ret;
+	spin_lock_irqsave(&dwc->lock, flags);
+	if (dwc->gadget_driver)
+		dwc3_disconnect_gadget(dwc);
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	return 0;
 }

 int dwc3_gadget_resume(struct dwc3 *dwc)
--
2.49.0.472.ge94155a9ec-goog