interconnect: Add sync state support

The bootloaders often do some initial configuration of the interconnects
in the system and we want to keep this configuration until all consumers
have probed and expressed their bandwidth needs. This is because we don't
want to change the configuration by starting to disable unused paths until
every user had a chance to request the amount of bandwidth it needs.

To accomplish this we will implement an interconnect specific sync_state
callback which will synchronize (aggregate and set) the current bandwidth
settings when all consumers have been probed.

Link: https://lore.kernel.org/r/20200825170152.6434-3-georgi.djakov@linaro.org
Reviewed-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index cf07491b7415be7363f253d28259e60f8a834735..b94c6c2b8ff96f0444a7a6942c18fd443b4222fa 100644 (file)
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -26,6 +26,8 @@
 
 static DEFINE_IDR(icc_idr);
 static LIST_HEAD(icc_providers);
+static int providers_count;
+static bool synced_state;
 static DEFINE_MUTEX(icc_lock);
 static struct dentry *icc_debugfs_dir;
 
@@ -267,6 +269,12 @@ static int aggregate_requests(struct icc_node *node)
                }
                p->aggregate(node, r->tag, avg_bw, peak_bw,
                             &node->avg_bw, &node->peak_bw);
+
+               /* during boot use the initial bandwidth as a floor value */
+               if (!synced_state) {
+                       node->avg_bw = max(node->avg_bw, node->init_avg);
+                       node->peak_bw = max(node->peak_bw, node->init_peak);
+               }
        }
 
        return 0;
@@ -931,6 +939,19 @@ void icc_node_add(struct icc_node *node, struct icc_provider *provider)
        node->provider = provider;
        list_add_tail(&node->node_list, &provider->nodes);
 
+       /* get the initial bandwidth values and sync them with hardware */
+       if (provider->get_bw) {
+               provider->get_bw(node, &node->init_avg, &node->init_peak);
+       } else {
+               node->init_avg = INT_MAX;
+               node->init_peak = INT_MAX;
+       }
+       node->avg_bw = node->init_avg;
+       node->peak_bw = node->init_peak;
+       provider->set(node, node);
+       node->avg_bw = 0;
+       node->peak_bw = 0;
+
        mutex_unlock(&icc_lock);
 }
 EXPORT_SYMBOL_GPL(icc_node_add);
@@ -1026,8 +1047,54 @@ int icc_provider_del(struct icc_provider *provider)
 }
 EXPORT_SYMBOL_GPL(icc_provider_del);
 
+static int of_count_icc_providers(struct device_node *np)
+{
+       struct device_node *child;
+       int count = 0;
+
+       for_each_available_child_of_node(np, child) {
+               if (of_property_read_bool(child, "#interconnect-cells"))
+                       count++;
+               count += of_count_icc_providers(child);
+       }
+       of_node_put(np);
+
+       return count;
+}
+
+void icc_sync_state(struct device *dev)
+{
+       struct icc_provider *p;
+       struct icc_node *n;
+       static int count;
+
+       count++;
+
+       if (count < providers_count)
+               return;
+
+       mutex_lock(&icc_lock);
+       synced_state = true;
+       list_for_each_entry(p, &icc_providers, provider_list) {
+               dev_dbg(p->dev, "interconnect provider is in synced state\n");
+               list_for_each_entry(n, &p->nodes, node_list) {
+                       if (n->init_avg || n->init_peak) {
+                               aggregate_requests(n);
+                               p->set(n, n);
+                       }
+               }
+       }
+       mutex_unlock(&icc_lock);
+}
+EXPORT_SYMBOL_GPL(icc_sync_state);
+
 static int __init icc_init(void)
 {
+       struct device_node *root = of_find_node_by_path("/");
+
+       providers_count = of_count_icc_providers(root);
+       of_node_put(root);
+
        icc_debugfs_dir = debugfs_create_dir("interconnect", NULL);
        debugfs_create_file("interconnect_summary", 0444,
                            icc_debugfs_dir, NULL, &icc_summary_fops);

diff --git a/include/linux/interconnect-provider.h b/include/linux/interconnect-provider.h
index 520f70fe5a313c3b88cc8487d21ff85aafb55d2b..f713308b8a8f42118fedfc9c9d84b291f54e7288 100644 (file)
--- a/include/linux/interconnect-provider.h
+++ b/include/linux/interconnect-provider.h
@@ -75,6 +75,8 @@ struct icc_provider {
  * @req_list: a list of QoS constraint requests associated with this node
  * @avg_bw: aggregated value of average bandwidth requests from all consumers
  * @peak_bw: aggregated value of peak bandwidth requests from all consumers
+ * @init_avg: average bandwidth value that is read from the hardware during init
+ * @init_peak: peak bandwidth value that is read from the hardware during init
  * @data: pointer to private data
  */
 struct icc_node {
@@ -91,6 +93,8 @@ struct icc_node {
        struct hlist_head       req_list;
        u32                     avg_bw;
        u32                     peak_bw;
+       u32                     init_avg;
+       u32                     init_peak;
        void                    *data;
 };
 
@@ -108,6 +112,7 @@ int icc_nodes_remove(struct icc_provider *provider);
 int icc_provider_add(struct icc_provider *provider);
 int icc_provider_del(struct icc_provider *provider);
 struct icc_node *of_icc_get_from_provider(struct of_phandle_args *spec);
+void icc_sync_state(struct device *dev);
 
 #else