[PATCH v3 3/8] usb: dwc3: make controller clear transfer resources after complete

[Anurag Kumar Vulisha]

To start transfer with another stream id, controller needs to free
previously allocated transfer resource. This will be automatically
done by the controller at the time of XferComplete Event. This
patch updates the code to issue XferComplete event once all transfers
are done by setting LST bit in the ctrl field of the last TRB.

Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha@xxxxxxxxxx>
Reviewed-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx>
---
 Changes in v3:
	1. Added the changes suggested by "Thinh Nguyen"

 Changes in v2:
	1. None
---
 drivers/usb/dwc3/gadget.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 43d63a8..13ea282 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -571,7 +571,8 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
 
 	if (usb_ss_max_streams(comp_desc) && usb_endpoint_xfer_bulk(desc)) {
 		params.param1 |= DWC3_DEPCFG_STREAM_CAPABLE
-			| DWC3_DEPCFG_STREAM_EVENT_EN;
+			| DWC3_DEPCFG_STREAM_EVENT_EN
+			| DWC3_DEPCFG_XFER_COMPLETE_EN;
 		dep->stream_capable = true;
 	}
 
@@ -995,6 +996,15 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_trb *trb,
 	if (chain)
 		trb->ctrl |= DWC3_TRB_CTRL_CHN;
 
+	/*
+	 * To issue start transfer on another stream, controller need to free
+	 * previously acquired transfer resource. Setting the LST bit in
+	 * last TRB makes the controller clear transfer resource for that
+	 * endpoint, allowing to start another stream on that endpoint.
+	 */
+	else if (dep->stream_capable)
+		trb->ctrl |= DWC3_TRB_CTRL_LST;
+
 	if (usb_endpoint_xfer_bulk(dep->endpoint.desc) && dep->stream_capable)
 		trb->ctrl |= DWC3_TRB_CTRL_SID_SOFN(stream_id);
 
@@ -2268,7 +2278,7 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
 	if (event->status & DEPEVT_STATUS_SHORT && !chain)
 		return 1;
 
-	if (event->status & DEPEVT_STATUS_IOC)
+	if (event->status & (DEPEVT_STATUS_IOC | DEPEVT_STATUS_LST))
 		return 1;
 
 	return 0;
@@ -2457,6 +2467,11 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
 	}
 
 	switch (event->endpoint_event) {
+	case DWC3_DEPEVT_XFERCOMPLETE:
+		if (!dep->stream_capable)
+			break;
+		dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
+		/* Fall Through */
 	case DWC3_DEPEVT_XFERINPROGRESS:
 		dwc3_gadget_endpoint_transfer_in_progress(dep, event);
 		break;
@@ -2472,7 +2487,6 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
 		}
 		break;
 	case DWC3_DEPEVT_STREAMEVT:
-	case DWC3_DEPEVT_XFERCOMPLETE:
 	case DWC3_DEPEVT_RXTXFIFOEVT:
 		break;
 	}
-- 
2.1.1