usb: dwc3: gadget: issue Update Transfer command after queuing isoc request

Issue an Update Transfer command after queuing a request to an isoc
EP with an active transfer. This is required according to the dwc3
databook. Pratyush Anand reports that this fixes a problem he was
having with Isoc IN transfers.

Tested-by: Pratyush Anand<pratyush.anand@st.com>
Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 49ee83ed68b754612c94a21240e66977403b82e6..31ffc5c273543a6c35068837c212347d83207ffc 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -957,10 +957,12 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep, u16 cmd_param,
        }
 
        dep->flags |= DWC3_EP_BUSY;
-       dep->res_trans_idx = dwc3_gadget_ep_get_transfer_index(dwc,
-                       dep->number);
 
-       WARN_ON_ONCE(!dep->res_trans_idx);
+       if (start_new) {
+               dep->res_trans_idx = dwc3_gadget_ep_get_transfer_index(dwc,
+                               dep->number);
+               WARN_ON_ONCE(!dep->res_trans_idx);
+       }
 
        return 0;
 }
@@ -994,28 +996,37 @@ static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
 
        list_add_tail(&req->list, &dep->request_list);
 
+       if (usb_endpoint_xfer_isoc(dep->desc) && (dep->flags & DWC3_EP_BUSY))
+               dep->flags |= DWC3_EP_PENDING_REQUEST;
+
        /*
-        * There is one special case: XferNotReady with
-        * empty list of requests. We need to kick the
-        * transfer here in that situation, otherwise
-        * we will be NAKing forever.
+        * There are two special cases:
         *
-        * If we get XferNotReady before gadget driver
-        * has a chance to queue a request, we will ACK
-        * the IRQ but won't be able to receive the data
-        * until the next request is queued. The following
-        * code is handling exactly that.
+        * 1. XferNotReady with empty list of requests. We need to kick the
+        *    transfer here in that situation, otherwise we will be NAKing
+        *    forever. If we get XferNotReady before gadget driver has a
+        *    chance to queue a request, we will ACK the IRQ but won't be
+        *    able to receive the data until the next request is queued.
+        *    The following code is handling exactly that.
+        *
+        * 2. XferInProgress on Isoc EP with an active transfer. We need to
+        *    kick the transfer here after queuing a request, otherwise the
+        *    core may not see the modified TRB(s).
         */
        if (dep->flags & DWC3_EP_PENDING_REQUEST) {
-               int ret;
-               int start_trans;
+               int     ret;
+               int     start_trans = 1;
+               u8      trans_idx = dep->res_trans_idx;
 
-               start_trans = 1;
                if (usb_endpoint_xfer_isoc(dep->desc) &&
-                               (dep->flags & DWC3_EP_BUSY))
+                               (dep->flags & DWC3_EP_BUSY)) {
                        start_trans = 0;
+                       WARN_ON_ONCE(!trans_idx);
+               } else {
+                       trans_idx = 0;
+               }
 
-               ret = __dwc3_gadget_kick_transfer(dep, 0, start_trans);
+               ret = __dwc3_gadget_kick_transfer(dep, trans_idx, start_trans);
                if (ret && ret != -EBUSY) {
                        struct dwc3     *dwc = dep->dwc;