firewire: Implement gap count optimization.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 67 insertions, 9 deletions

diff --git a/drivers/firewire/fw-topology.c b/drivers/firewire/fw-topology.c
index 684d87d99775..d3131e7d52fa 100644
--- a/drivers/firewire/fw-topology.c
+++ b/drivers/firewire/fw-topology.c
@@ -113,6 +113,44 @@ static struct fw_node *fw_node_create(u32 sid, int port_count, int color)
         return node;
 }
 
+/* Compute the maximum hop count for this node and it's children.  The
+ * maximum hop count is the maximum number of connections between any
+ * two nodes in the subtree rooted at this node.  We need this for
+ * setting the gap count.  As we build the tree bottom up in
+ * build_tree() below, this is fairly easy to do: for each node we
+ * maintain the max hop count and the max depth, ie the number of hops
+ * to the furthest leaf.  Computing the max hop count breaks down into
+ * two cases: either the path goes through this node, in which case
+ * the hop count is the sum of the two biggest child depths plus 2.
+ * Or it could be the case that the max hop path is entirely
+ * containted in a child tree, in which case the max hop count is just
+ * the max hop count of this child.
+ */
+static void update_hop_count(struct fw_node *node)
+{
+        int depths[2] = { -1, -1 };
+        int max_child_hops = 0;
+        int i;
+
+        for (i = 0; i < node->port_count; i++) {
+                if (node->ports[i].node == NULL)
+                        continue;
+
+                if (node->ports[i].node->max_hops > max_child_hops)
+                        max_child_hops = node->ports[i].node->max_hops;
+
+                if (node->ports[i].node->max_depth > depths[0]) {
+                        depths[1] = depths[0];
+                        depths[0] = node->ports[i].node->max_depth;
+                } else if (node->ports[i].node->max_depth > depths[1])
+                        depths[1] = node->ports[i].node->max_depth;
+        }
+
+        node->max_depth = depths[0] + 1;
+        node->max_hops = max(max_child_hops, depths[0] + depths[1] + 2);
+}
+
+
 /**
  * build_tree - Build the tree representation of the topology
  * @self_ids: array of self IDs to create the tree from
@@ -131,6 +169,7 @@ static struct fw_node *build_tree(struct fw_card *card)
         struct list_head stack, *h;
         u32 *sid, *next_sid, *end, q;
         int i, port_count, child_port_count, phy_id, parent_count, stack_depth;
+        int gap_count, topology_type;
 
         local_node = NULL;
         node = NULL;
@@ -140,6 +179,8 @@ static struct fw_node *build_tree(struct fw_card *card)
         end = sid + card->self_id_count;
         phy_id = 0;
         card->irm_node = NULL;
+        gap_count = self_id_gap_count(*sid);
+        topology_type = 0;
 
         while (sid < end) {
                 next_sid = count_ports(sid, &port_count, &child_port_count);
@@ -179,6 +220,11 @@ static struct fw_node *build_tree(struct fw_card *card)
                 if (self_id_contender(q))
                         card->irm_node = node;
 
+                if (node->phy_speed == SCODE_BETA)
+                        topology_type |= FW_TOPOLOGY_B;
+                else
+                        topology_type |= FW_TOPOLOGY_A;
+
                 parent_count = 0;
 
                 for (i = 0; i < port_count; i++) {
@@ -223,11 +269,21 @@ static struct fw_node *build_tree(struct fw_card *card)
                 list_add_tail(&node->link, &stack);
                 stack_depth += 1 - child_port_count;
 
+                /* If all PHYs does not report the same gap count
+                 * setting, we fall back to 63 which will force a gap
+                 * count reconfiguration and a reset. */
+                if (self_id_gap_count(q) != gap_count)
+                        gap_count = 63;
+
+                update_hop_count(node);
+
                 sid = next_sid;
                 phy_id++;
         }
 
         card->root_node = node;
+        card->gap_count = gap_count;
+        card->topology_type = topology_type;
 
         return local_node;
 }
@@ -286,7 +342,8 @@ report_found_node(struct fw_card *card,
         int b_path = (node->phy_speed == SCODE_BETA);
 
         if (parent != NULL) {
-                node->max_speed = min(parent->max_speed, node->phy_speed);
+                node->max_speed = min((u8)parent->max_speed,
+                                      (u8)node->phy_speed);
                 node->b_path = parent->b_path && b_path;
         } else {
                 node->max_speed = node->phy_speed;
@@ -329,7 +386,7 @@ static void move_tree(struct fw_node *node0, struct fw_node *node1, int port)
  * as we go.
  */
 static void
-update_tree(struct fw_card *card, struct fw_node *root, int *changed)
+update_tree(struct fw_card *card, struct fw_node *root)
 {
         struct list_head list0, list1;
         struct fw_node *node0, *node1;
@@ -342,7 +399,6 @@ update_tree(struct fw_card *card, struct fw_node *root, int *changed)
 
         node0 = fw_node(list0.next);
         node1 = fw_node(list1.next);
-        *changed = 0;
 
         while (&node0->link != &list0) {
 
@@ -358,6 +414,7 @@ update_tree(struct fw_card *card, struct fw_node *root, int *changed)
                 node0->color = card->color;
                 node0->link_on = node1->link_on;
                 node0->initiated_reset = node1->initiated_reset;
+                node0->max_hops = node1->max_hops;
                 node1->color = card->color;
                 fw_node_event(card, node0, event);
 
@@ -386,7 +443,6 @@ update_tree(struct fw_card *card, struct fw_node *root, int *changed)
                                 for_each_fw_node(card, node0->ports[i].node,
                                                  report_lost_node);
                                 node0->ports[i].node = NULL;
-                                *changed = 1;
                         } else if (node1->ports[i].node) {
                                 /* One or more node were connected to
                                  * this port. Move the new nodes into
@@ -395,7 +451,6 @@ update_tree(struct fw_card *card, struct fw_node *root, int *changed)
                                 move_tree(node0, node1, i);
                                 for_each_fw_node(card, node0->ports[i].node,
                                                  report_found_node);
-                                *changed = 1;
                         }
                 }
 
@@ -411,12 +466,17 @@ fw_core_handle_bus_reset(struct fw_card *card,
 {
         struct fw_node *local_node;
         unsigned long flags;
-        int changed;
 
         fw_flush_transactions(card);
 
         spin_lock_irqsave(&card->lock, flags);
 
+        /* If the new topology has a different self_id_count the topology
+         * changed, either nodes were added or removed. In that case we
+         * reset the IRM reset counter. */
+        if (card->self_id_count != self_id_count)
+                card->irm_retries = 0;
+
         card->node_id = node_id;
         card->self_id_count = self_id_count;
         card->generation = generation;
@@ -433,9 +493,7 @@ fw_core_handle_bus_reset(struct fw_card *card,
                 card->local_node = local_node;
                 for_each_fw_node(card, local_node, report_found_node);
         } else {
-                update_tree(card, local_node, &changed);
-                if (changed)
-                        card->irm_retries = 0;
+                update_tree(card, local_node);
         }
 
         /* If we're not the root node, we may have to do some IRM work. */