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Message-ID: <20250804080809.1700691-1-khtsai@google.com>
Date: Mon, 4 Aug 2025 16:08:05 +0800
From: Kuen-Han Tsai <khtsai@...gle.com>
To: Thinh.Nguyen@...opsys.com, gregkh@...uxfoundation.org
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
Kuen-Han Tsai <khtsai@...gle.com>
Subject: [RFC PATCH] usb: dwc3: Ignore late xferNotReady event to prevent halt timeout
During a device-initiated disconnect, an xferNotReady event for an ISOC
IN endpoint can be received after the End Transfer command has already
completed.
This late event incorrectly triggers a new Start Transfer, which
prevents the controller from halting and results in a DSTS.DEVCTRLHLT
bit polling timeout.
Ignore the late xferNotReady event if the controller is already in a
disconnected state.
Signed-off-by: Kuen-Han Tsai <khtsai@...gle.com>
---
Tracing:
# Stop active transfers by sending End Transfer commands
android.hardwar-913 [004] d..1. 6172.855517: dwc3_gadget_ep_cmd: ep1out: cmd 'End Transfer' [20d08] params 00000000 00000000 00000000 --> status: Successful
android.hardwar-913 [004] dn.1. 6172.855734: dwc3_gadget_ep_cmd: ep1in: cmd 'End Transfer' [40d08] params 00000000 00000000 00000000 --> status: Successful
...
# Recieve an xferNotReady event on an ISOC IN endpoint
irq/991-dwc3-29741 [000] D..1. 6172.856166: dwc3_event: event (35d010c6): ep1in: Transfer Not Ready [000035d0] (Not Active)
irq/991-dwc3-29741 [000] D..1. 6172.856190: dwc3_gadget_ep_cmd: ep1in: cmd 'Start Transfer' [35d60406] params 00000000 ffffb620 00000000 --> status: Successful
android.hardwar-913 [004] dn.1. 6172.868130: dwc3_gadget_ep_cmd: ep2in: cmd 'End Transfer' [30d08] params 00000000 00000000 00000000 --> status: Timed Out
...
# Start polling DSTS.DEVCTRLHLT
android.hardwar-913 [000] ..... 6172.869253: dwc3_gadget_run_stop: start polling DWC3_DSTS_DEVCTRLHLT
...
# HALT timeout and show the endpoint status for debugging
android.hardwar-913 [004] ..... 6177.479946: dwc3_gadget_run_stop: finish polling DWC3_DSTS_DEVCTRLHLT, is_on=0, reg=0
android.hardwar-913 [004] ..... 6177.479957: dwc3_gadget_ep_status: ep1out: mps 1024/2765 streams 16 burst 5 ring 64/56 flags E:swbp:>
android.hardwar-913 [004] ..... 6177.479958: dwc3_gadget_ep_status: ep1in: mps 1024/1024 streams 16 burst 2 ring 21/64 flags E:swBp:<
android.hardwar-913 [004] ..... 6177.479959: dwc3_gadget_ep_status: ep2out: mps 1024/2765 streams 16 burst 5 ring 56/48 flags e:swbp:>
---
drivers/usb/dwc3/gadget.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 25db36c63951..506391699a10 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -3896,7 +3896,8 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
dwc3_gadget_endpoint_transfer_in_progress(dep, event);
break;
case DWC3_DEPEVT_XFERNOTREADY:
- dwc3_gadget_endpoint_transfer_not_ready(dep, event);
+ if (dwc->connected)
+ dwc3_gadget_endpoint_transfer_not_ready(dep, event);
break;
case DWC3_DEPEVT_EPCMDCMPLT:
dwc3_gadget_endpoint_command_complete(dep, event);
--
2.50.1.565.gc32cd1483b-goog
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