On 11/17/2025 8:58 PM, Selvarasu Ganesan wrote:

This commit fixes the below warning that occurs when a StartTransfer command is issued for bulk or interrupt endpoints in `dwc3_gadget_ep_enable` while a previous transfer on the same endpoint is still in progress. The gadget functions drivers can invoke usb_ep_enable (which triggers a new StartTransfer command) before the earlier transfer has completed. Because the previous StartTransfer is still active, `dwc3_gadget_ep_disable` can skip the required `EndTransfer` due to `DWC3_EP_DELAY_STOP`, leading to the endpoint resources are busy for previous StartTransfer and warning ("No resource for ep") from gadget driver.

To resolve this, a check is added to `dwc3_gadget_ep_enable` that checks the `DWC3_EP_TRANSFER_STARTED` flag before issuing a new StartTransfer. By preventing a second StartTransfer on an already busy endpoint, the resource conflict is eliminated, the warning disappears, and potential kernel panics caused by `panic_on_warn` are avoided.

------------[ cut here ]------------ dwc3 13200000.dwc3: No resource for ep1out WARNING: CPU: 0 PID: 700 at drivers/usb/dwc3/gadget.c:398 dwc3_send_gadget_ep_cmd+0x2f8/0x76c Call trace: dwc3_send_gadget_ep_cmd+0x2f8/0x76c __dwc3_gadget_ep_enable+0x490/0x7c0 dwc3_gadget_ep_enable+0x6c/0xe4 usb_ep_enable+0x5c/0x15c mp_eth_stop+0xd4/0x11c __dev_close_many+0x160/0x1c8 __dev_change_flags+0xfc/0x220 dev_change_flags+0x24/0x70 devinet_ioctl+0x434/0x524 inet_ioctl+0xa8/0x224 sock_do_ioctl+0x74/0x128 sock_ioctl+0x3bc/0x468 __arm64_sys_ioctl+0xa8/0xe4 invoke_syscall+0x58/0x10c el0_svc_common+0xa8/0xdc do_el0_svc+0x1c/0x28 el0_svc+0x38/0x88 el0t_64_sync_handler+0x70/0xbc el0t_64_sync+0x1a8/0x1ac

Change-Id: Id292265a34448e566ef1ea882e313856423342dc

Required to remove change-id as mistakenly included, and going to post new version with remove change-id.

Fixes: a97ea994605e ("usb: dwc3: gadget: offset Start Transfer latency for bulk EPs") Cc: stable@vger.kernel.org Signed-off-by: Selvarasu Ganesan selvarasu.g@samsung.com

---

drivers/usb/dwc3/gadget.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index f95d1369bbc6..23e5c111da7c 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -951,8 +951,9 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action) * Issue StartTransfer here with no-op TRB so we can always rely on No * Response Update Transfer command. */

• if (usb_endpoint_xfer_bulk(desc) ||

• 	usb_endpoint_xfer_int(desc)) {
  

• if ((usb_endpoint_xfer_bulk(desc) ||

• 	usb_endpoint_xfer_int(desc)) &&
  

• 	!(dep->flags & DWC3_EP_TRANSFER_STARTED)) {
  

  struct dwc3_gadget_ep_cmd_params params; struct dwc3_trb *trb; dma_addr_t trb_dma;