+/**
+ * dwc3_ep_prev_trb() - Returns the previous TRB in the ring
+ * @dep: The endpoint with the TRB ring
+ * @index: The index of the current TRB in the ring
+ *
+ * Returns the TRB prior to the one pointed to by the index. If the
+ * index is 0, we will wrap backwards, skip the link TRB, and return
+ * the one just before that.
+ */
+static struct dwc3_trb *dwc3_ep_prev_trb(struct dwc3_ep *dep, u8 index)
+{
+ if (!index)
+ index = DWC3_TRB_NUM - 2;
+ else
+ index = dep->trb_enqueue - 1;
+
+ return &dep->trb_pool[index];
+}
+