usb: dwc3: gadget: Simplify skipping of link TRBs

Make the skipping of the link TRBS built-in to the increment operation.
This simplifies the code wherever we increment the trb index and ensures
that we never end up pointing to a link trb.

Signed-off-by: John Youn <johnyoun@synopsys.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 f38db3b..24bb942 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -145,21 +145,29 @@ int dwc3_gadget_set_link_state(struct dwc3 *dwc, enum dwc3_link_state state)
        return -ETIMEDOUT;
 }
 
-static void dwc3_ep_inc_enq(struct dwc3_ep *dep)
+/**
+ * dwc3_ep_inc_trb() - Increment a TRB index.
+ * @index - Pointer to the TRB index to increment.
+ *
+ * The index should never point to the link TRB. After incrementing,
+ * if it is point to the link TRB, wrap around to the beginning. The
+ * link TRB is always at the last TRB entry.
+ */
+static void dwc3_ep_inc_trb(u8 *index)
 {
-       dep->trb_enqueue++;
-       dep->trb_enqueue %= DWC3_TRB_NUM;
+       (*index)++;
+       if (*index == (DWC3_TRB_NUM - 1))
+               *index = 0;
 }
 
-static void dwc3_ep_inc_deq(struct dwc3_ep *dep)
+static void dwc3_ep_inc_enq(struct dwc3_ep *dep)
 {
-       dep->trb_dequeue++;
-       dep->trb_dequeue %= DWC3_TRB_NUM;
+       dwc3_ep_inc_trb(&dep->trb_enqueue);
 }
 
-static int dwc3_ep_is_last_trb(unsigned int index)
+static void dwc3_ep_inc_deq(struct dwc3_ep *dep)
 {
-       return index == DWC3_TRB_NUM - 1;
+       dwc3_ep_inc_trb(&dep->trb_dequeue);
 }
 
 void dwc3_gadget_giveback(struct dwc3_ep *dep, struct dwc3_request *req,
@@ -172,13 +180,6 @@ void dwc3_gadget_giveback(struct dwc3_ep *dep, struct dwc3_request *req,
                i = 0;
                do {
                        dwc3_ep_inc_deq(dep);
-                       /*
-                        * Skip LINK TRB. We can't use req->trb and check for
-                        * DWC3_TRBCTL_LINK_TRB because it points the TRB we
-                        * just completed (not the LINK TRB).
-                        */
-                       if (dwc3_ep_is_last_trb(dep->trb_dequeue))
-                               dwc3_ep_inc_deq(dep);
                } while(++i < req->request.num_mapped_sgs);
                req->started = false;
        }
@@ -785,9 +786,6 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
        }
 
        dwc3_ep_inc_enq(dep);
-       /* Skip the LINK-TRB */
-       if (dwc3_ep_is_last_trb(dep->trb_enqueue))
-               dwc3_ep_inc_enq(dep);
 
        trb->size = DWC3_TRB_SIZE_LENGTH(length);
        trb->bpl = lower_32_bits(dma);