[PATCH 5.5 044/367] usb: dwc3: gadget: Delay starting transfer

Greg Kroah-Hartman
2020-02-10T12:52:07Z

From: Thinh Nguyen <Thinh.Nguyen@synopsys.com>

commit da10bcdd6f70dc9977f2cf18f4783cf78520623a upstream.

If the END_TRANSFER command hasn't completed yet, then don't send the
START_TRANSFER command. The controller may not be able to start if
that's the case. Some controller revisions depend on this. See
commit 76a638f8ac0d ("usb: dwc3: gadget: wait for End Transfer to
complete"). Let's only send START_TRANSFER command after the
END_TRANSFER command had completed.

Fixes: 3aec99154db3 ("usb: dwc3: gadget: remove DWC3_EP_END_TRANSFER_PENDING")
Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/dwc3/core.h | 1 +
drivers/usb/dwc3/gadget.c | 11 +++++++++++
2 files changed, 12 insertions(+)

--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -690,6 +690,7 @@ struct dwc3_ep {
#define DWC3_EP_TRANSFER_STARTED BIT(3)
#define DWC3_EP_END_TRANSFER_PENDING BIT(4)
#define DWC3_EP_PENDING_REQUEST BIT(5)
+#define DWC3_EP_DELAY_START BIT(6)

/* This last one is specific to EP0 */
#define DWC3_EP0_DIR_IN BIT(31)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1447,6 +1447,12 @@ static int __dwc3_gadget_ep_queue(struct
list_add_tail(&req->list, &dep->pending_list);
req->status = DWC3_REQUEST_STATUS_QUEUED;

+ /* Start the transfer only after the END_TRANSFER is completed */
+ if (dep->flags & DWC3_EP_END_TRANSFER_PENDING) {
+ dep->flags |= DWC3_EP_DELAY_START;
+ return 0;
+ }
+
/*
* NOTICE: Isochronous endpoints should NEVER be prestarted. We must
* wait for a XferNotReady event so we will know what's the current
@@ -2628,6 +2634,11 @@ static void dwc3_endpoint_interrupt(stru
dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
dwc3_gadget_ep_cleanup_cancelled_requests(dep);
+ if ((dep->flags & DWC3_EP_DELAY_START) &&
+ !usb_endpoint_xfer_isoc(dep->endpoint.desc))
+ __dwc3_gadget_kick_transfer(dep);
+
+ dep->flags &= ~DWC3_EP_DELAY_START;
}
break;
case DWC3_DEPEVT_STREAMEVT: