usb: cdns3: gadget: toggle cycle bit before reset endpoint

commit 4bf2dd65135a2d7fe202f7c10d65b51bcf645ac6 upstream.

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 <peter.chen@nxp.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200219141455.23257-3-peter.chen@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
index 49a189ebae29eac58623355da2c69c9c7a9ca391..f624cc87cbabc47a6a1a7a64728bb58fd859afa9 100644 (file)
--- a/drivers/usb/cdns3/gadget.c
+++ b/drivers/usb/cdns3/gadget.c
@@ -2152,11 +2152,21 @@ 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 */
@@ -2167,10 +2177,11 @@ 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;