usb: dwc3: gadget: Keep TRBs in request order

If we couldn't finish preparing all the TRBs of a request, don't prepare
the next request. Otherwise, the TRBs order will be mixed up and the
controller will process the wrong TRB. This is a corner case where
there's not enough TRBs for a request that needs the extra TRB but
there's still 1 available TRB in the pool.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 327cd556e8dbfc6fb02766ce0418f1845a86d3a1..ff924656f6908c0b5c818feeacce3009da1ea972 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1274,7 +1274,7 @@ static int dwc3_prepare_trbs(struct dwc3_ep *dep)
        list_for_each_entry(req, &dep->started_list, list) {
                if (req->num_pending_sgs > 0) {
                        ret = dwc3_prepare_trbs_sg(dep, req);
-                       if (!ret)
+                       if (!ret || req->num_pending_sgs)
                                return ret;
                }
 
@@ -1303,10 +1303,13 @@ static int dwc3_prepare_trbs(struct dwc3_ep *dep)
                req->num_queued_sgs     = 0;
                req->num_pending_sgs    = req->request.num_mapped_sgs;
 
-               if (req->num_pending_sgs > 0)
+               if (req->num_pending_sgs > 0) {
                        ret = dwc3_prepare_trbs_sg(dep, req);
-               else
+                       if (req->num_pending_sgs)
+                               return ret;
+               } else {
                        ret = dwc3_prepare_trbs_linear(dep, req);
+               }
 
                if (!ret || !dwc3_calc_trbs_left(dep))
                        return ret;