[PATCH] usb: dwc3: gadget: Fix START_TRANSFER link state check

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

The START_TRANSFER command needs to be executed while in ON/U0 link
state (with an exception during register initialization). Don't use
dwc->link_state to check this since the driver only tracks the link
state when the link state change interrupt is enabled. Check the link
state from DSTS register instead.

Note that often the host already brings the device out of low power
before it sends/requests the next transfer. So, the user won't see any
issue when the device starts transfer then. This issue is more
noticeable in cases when the device delays starting transfer, which can
happen during delayed control status after the host put the device in
low power.

Cc: <stable@vger.kernel.org>
Fixes: 799e9dc82968 ("usb: dwc3: gadget: conditionally disable Link State change events")
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
 drivers/usb/dwc3/gadget.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 6227641f2d31..1a632a3faf7f 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -308,13 +308,12 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 	}
 
 	if (DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_STARTTRANSFER) {
-		int		needs_wakeup;
+		int link_state;
 
-		needs_wakeup = (dwc->link_state == DWC3_LINK_STATE_U1 ||
-				dwc->link_state == DWC3_LINK_STATE_U2 ||
-				dwc->link_state == DWC3_LINK_STATE_U3);
-
-		if (unlikely(needs_wakeup)) {
+		link_state = dwc3_gadget_get_link_state(dwc);
+		if (link_state == DWC3_LINK_STATE_U1 ||
+		    link_state == DWC3_LINK_STATE_U2 ||
+		    link_state == DWC3_LINK_STATE_U3) {
 			ret = __dwc3_gadget_wakeup(dwc);
 			dev_WARN_ONCE(dwc->dev, ret, "wakeup failed --> %d\n",
 					ret);
@@ -1989,6 +1988,8 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
 	case DWC3_LINK_STATE_RESET:
 	case DWC3_LINK_STATE_RX_DET:	/* in HS, means Early Suspend */
 	case DWC3_LINK_STATE_U3:	/* in HS, means SUSPEND */
+	case DWC3_LINK_STATE_U2:	/* in HS, means Sleep (L1) */
+	case DWC3_LINK_STATE_U1:
 	case DWC3_LINK_STATE_RESUME:
 		break;
 	default:

base-commit: 4b853c236c7b5161a2e444bd8b3c76fe5aa5ddcb
-- 
2.28.0