usb: dwc3: gadget: fix for short pkts during chained xfers

DWC3 has one interesting peculiarity with chained
transfers. If we setup N chained transfers and we
get a short packet before processing all N TRBs,
DWC3 will (conditionally) issue a XferComplete or
XferInProgress event and retire all TRBs from the
one which got a short packet to the last without
clearing their HWO bits.

This means SW must clear HWO bit manually, which
this patch is doing.

Cc: <stable@vger.kernel.org>
Cc: Brian E Rogers <brian.e.rogers@intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 863c306..241f5c7 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1955,7 +1955,8 @@ static void dwc3_gadget_free_endpoints(struct dwc3 *dwc)
 
 static int __dwc3_cleanup_done_trbs(struct dwc3 *dwc, struct dwc3_ep *dep,
                struct dwc3_request *req, struct dwc3_trb *trb,
-               const struct dwc3_event_depevt *event, int status)
+               const struct dwc3_event_depevt *event, int status,
+               int chain)
 {
        unsigned int            count;
        unsigned int            s_pkt = 0;
@@ -1964,6 +1965,19 @@ static int __dwc3_cleanup_done_trbs(struct dwc3 *dwc, struct dwc3_ep *dep,
        dep->queued_requests--;
        trace_dwc3_complete_trb(dep, trb);
 
+       /*
+        * If we're in the middle of series of chained TRBs and we
+        * receive a short transfer along the way, DWC3 will skip
+        * through all TRBs including the last TRB in the chain (the
+        * where CHN bit is zero. DWC3 will also avoid clearing HWO
+        * bit and SW has to do it manually.
+        *
+        * We're going to do that here to avoid problems of HW trying
+        * to use bogus TRBs for transfers.
+        */
+       if (chain && (trb->ctrl & DWC3_TRB_CTRL_HWO))
+               trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
+
        if ((trb->ctrl & DWC3_TRB_CTRL_HWO) && status != -ESHUTDOWN)
                /*
                 * We continue despite the error. There is not much we
@@ -1975,6 +1989,7 @@ static int __dwc3_cleanup_done_trbs(struct dwc3 *dwc, struct dwc3_ep *dep,
                 */
                dev_err(dwc->dev, "%s's TRB (%p) still owned by HW\n",
                                dep->name, trb);
+
        count = trb->size & DWC3_TRB_SIZE_MASK;
 
        if (dep->direction) {
@@ -2036,10 +2051,13 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
        int                     ret;
 
        do {
+               int chain;
+
                req = next_request(&dep->started_list);
                if (WARN_ON_ONCE(!req))
                        return 1;
 
+               chain = req->request.num_mapped_sgs > 0;
                i = 0;
                do {
                        slot = req->first_trb_index + i;
@@ -2049,9 +2067,8 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
                        trb = &dep->trb_pool[slot];
                        count += trb->size & DWC3_TRB_SIZE_MASK;
 
-
                        ret = __dwc3_cleanup_done_trbs(dwc, dep, req, trb,
-                                       event, status);
+                                       event, status, chain);
                        if (ret)
                                break;
                } while (++i < req->request.num_mapped_sgs);