usb: xhci: refactor trb_in_td() to be static

Relocate trb_in_td() and marks it as static, as it's exclusively utilized
in xhci-ring.c. This adjustment lays the groundwork for future rework of
the function.

The function's logic remains unchanged; only its access specifier is
altered to static and a redundant "else" is removed on line 325
(due to checkpatch.pl complaining).

Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20250306144954.3507700-11-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Epicurius

drivers/usb/host/xhci-ring.c

@@ -277,6 +277,67 @@ static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring,
 	}
 }
 
+/*
+ * If the suspect DMA address is a TRB in this TD, this function returns that
+ * TRB's segment. Otherwise it returns 0.
+ */
+static struct xhci_segment *trb_in_td(struct xhci_hcd *xhci, struct xhci_td *td,
+				      dma_addr_t suspect_dma, bool debug)
+{
+	dma_addr_t start_dma;
+	dma_addr_t end_seg_dma;
+	dma_addr_t end_trb_dma;
+	struct xhci_segment *cur_seg;
+
+	start_dma = xhci_trb_virt_to_dma(td->start_seg, td->start_trb);
+	cur_seg = td->start_seg;
+
+	do {
+		if (start_dma == 0)
+			return NULL;
+		/* We may get an event for a Link TRB in the middle of a TD */
+		end_seg_dma = xhci_trb_virt_to_dma(cur_seg,
+				&cur_seg->trbs[TRBS_PER_SEGMENT - 1]);
+		/* If the end TRB isn't in this segment, this is set to 0 */
+		end_trb_dma = xhci_trb_virt_to_dma(cur_seg, td->end_trb);
+
+		if (debug)
+			xhci_warn(xhci,
+				"Looking for event-dma %016llx trb-start %016llx trb-end %016llx seg-start %016llx seg-end %016llx\n",
+				(unsigned long long)suspect_dma,
+				(unsigned long long)start_dma,
+				(unsigned long long)end_trb_dma,
+				(unsigned long long)cur_seg->dma,
+				(unsigned long long)end_seg_dma);
+
+		if (end_trb_dma > 0) {
+			/* The end TRB is in this segment, so suspect should be here */
+			if (start_dma <= end_trb_dma) {
+				if (suspect_dma >= start_dma && suspect_dma <= end_trb_dma)
+					return cur_seg;
+			} else {
+				/* Case for one segment with
+				 * a TD wrapped around to the top
+				 */
+				if ((suspect_dma >= start_dma &&
+							suspect_dma <= end_seg_dma) ||
+						(suspect_dma >= cur_seg->dma &&
+						 suspect_dma <= end_trb_dma))
+					return cur_seg;
+			}
+			return NULL;
+		}
+		/* Might still be somewhere in this segment */
+		if (suspect_dma >= start_dma && suspect_dma <= end_seg_dma)
+			return cur_seg;
+
+		cur_seg = cur_seg->next;
+		start_dma = xhci_trb_virt_to_dma(cur_seg, &cur_seg->trbs[0]);
+	} while (cur_seg != td->start_seg);
+
+	return NULL;
+}
+
 /*
  * Return number of free normal TRBs from enqueue to dequeue pointer on ring.
  * Not counting an assumed link TRB at end of each TRBS_PER_SEGMENT sized segment.
@@ -2079,67 +2140,6 @@ static void handle_port_status(struct xhci_hcd *xhci, union xhci_trb *event)
 	spin_lock(&xhci->lock);
 }
 
-/*
- * If the suspect DMA address is a TRB in this TD, this function returns that
- * TRB's segment. Otherwise it returns 0.
- */
-struct xhci_segment *trb_in_td(struct xhci_hcd *xhci, struct xhci_td *td, dma_addr_t suspect_dma,
-			       bool debug)
-{
-	dma_addr_t start_dma;
-	dma_addr_t end_seg_dma;
-	dma_addr_t end_trb_dma;
-	struct xhci_segment *cur_seg;
-
-	start_dma = xhci_trb_virt_to_dma(td->start_seg, td->start_trb);
-	cur_seg = td->start_seg;
-
-	do {
-		if (start_dma == 0)
-			return NULL;
-		/* We may get an event for a Link TRB in the middle of a TD */
-		end_seg_dma = xhci_trb_virt_to_dma(cur_seg,
-				&cur_seg->trbs[TRBS_PER_SEGMENT - 1]);
-		/* If the end TRB isn't in this segment, this is set to 0 */
-		end_trb_dma = xhci_trb_virt_to_dma(cur_seg, td->end_trb);
-
-		if (debug)
-			xhci_warn(xhci,
-				"Looking for event-dma %016llx trb-start %016llx trb-end %016llx seg-start %016llx seg-end %016llx\n",
-				(unsigned long long)suspect_dma,
-				(unsigned long long)start_dma,
-				(unsigned long long)end_trb_dma,
-				(unsigned long long)cur_seg->dma,
-				(unsigned long long)end_seg_dma);
-
-		if (end_trb_dma > 0) {
-			/* The end TRB is in this segment, so suspect should be here */
-			if (start_dma <= end_trb_dma) {
-				if (suspect_dma >= start_dma && suspect_dma <= end_trb_dma)
-					return cur_seg;
-			} else {
-				/* Case for one segment with
-				 * a TD wrapped around to the top
-				 */
-				if ((suspect_dma >= start_dma &&
-							suspect_dma <= end_seg_dma) ||
-						(suspect_dma >= cur_seg->dma &&
-						 suspect_dma <= end_trb_dma))
-					return cur_seg;
-			}
-			return NULL;
-		} else {
-			/* Might still be somewhere in this segment */
-			if (suspect_dma >= start_dma && suspect_dma <= end_seg_dma)
-				return cur_seg;
-		}
-		cur_seg = cur_seg->next;
-		start_dma = xhci_trb_virt_to_dma(cur_seg, &cur_seg->trbs[0]);
-	} while (cur_seg != td->start_seg);
-
-	return NULL;
-}
-
 static void xhci_clear_hub_tt_buffer(struct xhci_hcd *xhci, struct xhci_td *td,
 		struct xhci_virt_ep *ep)
 {

drivers/usb/host/xhci.h

@@ -1884,8 +1884,6 @@ int xhci_set_interrupter_moderation(struct xhci_interrupter *ir,
 
 /* xHCI ring, segment, TRB, and TD functions */
 dma_addr_t xhci_trb_virt_to_dma(struct xhci_segment *seg, union xhci_trb *trb);
-struct xhci_segment *trb_in_td(struct xhci_hcd *xhci, struct xhci_td *td,
-			       dma_addr_t suspect_dma, bool debug);
 int xhci_is_vendor_info_code(struct xhci_hcd *xhci, unsigned int trb_comp_code);
 void xhci_ring_cmd_db(struct xhci_hcd *xhci);
 int xhci_queue_slot_control(struct xhci_hcd *xhci, struct xhci_command *cmd,