xHCI: dynamic ring expansion

If room_on_ring() check fails, try to expand the ring and check again.

When expand a ring, use a cached ring or allocate new segments, link
the original ring and the new ring or segments, update the original ring's
segment numbers and the last segment pointer.

Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Tested-by: Paul Zimmerman <Paul.Zimmerman@synopsys.com>

drivers/usb/host/xhci-mem.c

@@ -119,6 +119,34 @@ static void xhci_link_segments(struct xhci_hcd *xhci, struct xhci_segment *prev,
 	}
 }
 
+/*
+ * Link the ring to the new segments.
+ * Set Toggle Cycle for the new ring if needed.
+ */
+static void xhci_link_rings(struct xhci_hcd *xhci, struct xhci_ring *ring,
+		struct xhci_segment *first, struct xhci_segment *last,
+		unsigned int num_segs)
+{
+	struct xhci_segment *next;
+
+	if (!ring || !first || !last)
+		return;
+
+	next = ring->enq_seg->next;
+	xhci_link_segments(xhci, ring->enq_seg, first, ring->type);
+	xhci_link_segments(xhci, last, next, ring->type);
+	ring->num_segs += num_segs;
+	ring->num_trbs_free += (TRBS_PER_SEGMENT - 1) * num_segs;
+
+	if (ring->type != TYPE_EVENT && ring->enq_seg == ring->last_seg) {
+		ring->last_seg->trbs[TRBS_PER_SEGMENT-1].link.control
+			&= ~cpu_to_le32(LINK_TOGGLE);
+		last->trbs[TRBS_PER_SEGMENT-1].link.control
+			|= cpu_to_le32(LINK_TOGGLE);
+		ring->last_seg = last;
+	}
+}
+
 /* XXX: Do we need the hcd structure in all these functions? */
 void xhci_ring_free(struct xhci_hcd *xhci, struct xhci_ring *ring)
 {
@@ -287,6 +315,39 @@ static void xhci_reinit_cached_ring(struct xhci_hcd *xhci,
 	INIT_LIST_HEAD(&ring->td_list);
 }
 
+/*
+ * Expand an existing ring.
+ * Look for a cached ring or allocate a new ring which has same segment numbers
+ * and link the two rings.
+ */
+int xhci_ring_expansion(struct xhci_hcd *xhci, struct xhci_ring *ring,
+				unsigned int num_trbs, gfp_t flags)
+{
+	struct xhci_segment	*first;
+	struct xhci_segment	*last;
+	unsigned int		num_segs;
+	unsigned int		num_segs_needed;
+	int			ret;
+
+	num_segs_needed = (num_trbs + (TRBS_PER_SEGMENT - 1) - 1) /
+				(TRBS_PER_SEGMENT - 1);
+
+	/* Allocate number of segments we needed, or double the ring size */
+	num_segs = ring->num_segs > num_segs_needed ?
+			ring->num_segs : num_segs_needed;
+
+	ret = xhci_alloc_segments_for_ring(xhci, &first, &last,
+			num_segs, ring->cycle_state, ring->type, flags);
+	if (ret)
+		return -ENOMEM;
+
+	xhci_link_rings(xhci, ring, first, last, num_segs);
+	xhci_dbg(xhci, "ring expansion succeed, now has %d segments\n",
+			ring->num_segs);
+
+	return 0;
+}
+
 #define CTX_SIZE(_hcc) (HCC_64BYTE_CONTEXT(_hcc) ? 64 : 32)
 
 static struct xhci_container_ctx *xhci_alloc_container_ctx(struct xhci_hcd *xhci,
@@ -1361,18 +1422,8 @@ int xhci_endpoint_init(struct xhci_hcd *xhci,
 
 	type = usb_endpoint_type(&ep->desc);
 	/* Set up the endpoint ring */
-	/*
-	 * Isochronous endpoint ring needs bigger size because one isoc URB
-	 * carries multiple packets and it will insert multiple tds to the
-	 * ring.
-	 * This should be replaced with dynamic ring resizing in the future.
-	 */
-	if (usb_endpoint_xfer_isoc(&ep->desc))
-		virt_dev->eps[ep_index].new_ring =
-			xhci_ring_alloc(xhci, 8, 1, type, mem_flags);
-	else
-		virt_dev->eps[ep_index].new_ring =
-			xhci_ring_alloc(xhci, 1, 1, type, mem_flags);
+	virt_dev->eps[ep_index].new_ring =
+		xhci_ring_alloc(xhci, 1, 1, type, mem_flags);
 	if (!virt_dev->eps[ep_index].new_ring) {
 		/* Attempt to use the ring cache */
 		if (virt_dev->num_rings_cached == 0)

drivers/usb/host/xhci-ring.c

@@ -2490,6 +2490,8 @@ static void queue_trb(struct xhci_hcd *xhci, struct xhci_ring *ring,
 static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
 		u32 ep_state, unsigned int num_trbs, gfp_t mem_flags)
 {
+	unsigned int num_trbs_needed;
+
 	/* Make sure the endpoint has been added to xHC schedule */
 	switch (ep_state) {
 	case EP_STATE_DISABLED:
@@ -2517,11 +2519,32 @@ static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
 		 */
 		return -EINVAL;
 	}
-	if (!room_on_ring(xhci, ep_ring, num_trbs)) {
-		/* FIXME allocate more room */
-		xhci_err(xhci, "ERROR no room on ep ring\n");
-		return -ENOMEM;
-	}
+
+	while (1) {
+		if (room_on_ring(xhci, ep_ring, num_trbs))
+			break;
+
+		if (ep_ring == xhci->cmd_ring) {
+			xhci_err(xhci, "Do not support expand command ring\n");
+			return -ENOMEM;
+		}
+
+		if (ep_ring->enq_seg == ep_ring->deq_seg &&
+				ep_ring->dequeue > ep_ring->enqueue) {
+			xhci_err(xhci, "Can not expand the ring while dequeue "
+				"pointer has not passed the link TRB\n");
+			return -ENOMEM;
+		}
+
+		xhci_dbg(xhci, "ERROR no room on ep ring, "
+					"try ring expansion\n");
+		num_trbs_needed = num_trbs - ep_ring->num_trbs_free;
+		if (xhci_ring_expansion(xhci, ep_ring, num_trbs_needed,
+					mem_flags)) {
+			xhci_err(xhci, "Ring expansion failed\n");
+			return -ENOMEM;
+		}
+	};
 
 	if (enqueue_is_link_trb(ep_ring)) {
 		struct xhci_ring *ring = ep_ring;

drivers/usb/host/xhci.h

@@ -1622,6 +1622,8 @@ int xhci_endpoint_init(struct xhci_hcd *xhci, struct xhci_virt_device *virt_dev,
 		struct usb_device *udev, struct usb_host_endpoint *ep,
 		gfp_t mem_flags);
 void xhci_ring_free(struct xhci_hcd *xhci, struct xhci_ring *ring);
+int xhci_ring_expansion(struct xhci_hcd *xhci, struct xhci_ring *ring,
+				unsigned int num_trbs, gfp_t flags);
 void xhci_free_or_cache_endpoint_ring(struct xhci_hcd *xhci,
 		struct xhci_virt_device *virt_dev,
 		unsigned int ep_index);