xhci: remove xhci_stream_id_to_ring() helper

The one case that used this function can use the
xhci_triad_to_transfer_ring() helper instead.

Avoid having several functions doing basically the same thing.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20210129130044.206855-9-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-mem.c

@@ -592,23 +592,6 @@ struct xhci_ring *xhci_dma_to_transfer_ring(
 	return ep->ring;
 }
 
-struct xhci_ring *xhci_stream_id_to_ring(
-		struct xhci_virt_device *dev,
-		unsigned int ep_index,
-		unsigned int stream_id)
-{
-	struct xhci_virt_ep *ep = &dev->eps[ep_index];
-
-	if (stream_id == 0)
-		return ep->ring;
-	if (!ep->stream_info)
-		return NULL;
-
-	if (stream_id >= ep->stream_info->num_streams)
-		return NULL;
-	return ep->stream_info->stream_rings[stream_id];
-}
-
 /*
  * Change an endpoint's internal structure so it supports stream IDs.  The
  * number of requested streams includes stream 0, which cannot be used by device

drivers/usb/host/xhci-ring.c

@@ -3042,7 +3042,8 @@ static int prepare_transfer(struct xhci_hcd *xhci,
 	struct xhci_ring *ep_ring;
 	struct xhci_ep_ctx *ep_ctx = xhci_get_ep_ctx(xhci, xdev->out_ctx, ep_index);
 
-	ep_ring = xhci_stream_id_to_ring(xdev, ep_index, stream_id);
+	ep_ring = xhci_triad_to_transfer_ring(xhci, xdev->slot_id, ep_index,
+					      stream_id);
 	if (!ep_ring) {
 		xhci_dbg(xhci, "Can't prepare ring for bad stream ID %u\n",
 				stream_id);

drivers/usb/host/xhci.h

@@ -2050,10 +2050,6 @@ void xhci_free_device_endpoint_resources(struct xhci_hcd *xhci,
 struct xhci_ring *xhci_dma_to_transfer_ring(
 		struct xhci_virt_ep *ep,
 		u64 address);
-struct xhci_ring *xhci_stream_id_to_ring(
-		struct xhci_virt_device *dev,
-		unsigned int ep_index,
-		unsigned int stream_id);
 struct xhci_command *xhci_alloc_command(struct xhci_hcd *xhci,
 		bool allocate_completion, gfp_t mem_flags);
 struct xhci_command *xhci_alloc_command_with_ctx(struct xhci_hcd *xhci,