[v2,2/2] usb: cdns3: gadget: toggle cycle bit before reset endpoint

Commit Message

Peter Chen Feb. 19, 2020, 2:14 p.m. UTC

If there are TRBs pending during reset endpoint operation, the
DMA will advance after reset operation, but it isn't expected,
since the data is not yet available (For OUT, the data is not
yet available). After the data is ready, there won't be any
interrupt since the EP_TRADDR already points to next TRB entry
and doorbell is not set.

To fix it, it toggles cycle bit before reset operation, and restores
it after reset, it could avoid unexpected DMA advance due to
cycle bit is for software during the endpoint reset operation.

Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
Signed-off-by: Peter Chen <[e-mail]>
---
Changes for v2:
- Improve the comments.
- Using MACRO TRB_CYCLE at code

 drivers/usb/cdns3/gadget.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

Patch

diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
index 1d8a2af35bb0..3574dbb09366 100644
--- a/drivers/usb/cdns3/gadget.c
+++ b/drivers/usb/cdns3/gadget.c
@@ -2595,11 +2595,21 @@  int __cdns3_gadget_ep_clear_halt(struct cdns3_endpoint *priv_ep)
 {
 	struct cdns3_device *priv_dev = priv_ep->cdns3_dev;
 	struct usb_request *request;
+	struct cdns3_request *priv_req;
+	struct cdns3_trb *trb = NULL;
 	int ret;
 	int val;
 
 	trace_cdns3_halt(priv_ep, 0, 0);
 
+	request = cdns3_next_request(&priv_ep->pending_req_list);
+	if (request) {
+		priv_req = to_cdns3_request(request);
+		trb = priv_req->trb;
+		if (trb)
+			trb->control = trb->control ^ TRB_CYCLE;
+	}
+
 	writel(EP_CMD_CSTALL | EP_CMD_EPRST, &priv_dev->regs->ep_cmd);
 
 	/* wait for EPRST cleared */
@@ -2610,10 +2620,11 @@  int __cdns3_gadget_ep_clear_halt(struct cdns3_endpoint *priv_ep)
 
 	priv_ep->flags &= ~(EP_STALLED | EP_STALL_PENDING);
 
-	request = cdns3_next_request(&priv_ep->pending_req_list);
-
-	if (request)
+	if (request) {
+		if (trb)
+			trb->control = trb->control ^ TRB_CYCLE;
 		cdns3_rearm_transfer(priv_ep, 1);
+	}
 
 	cdns3_start_all_request(priv_dev, priv_ep);
 	return ret;