interconnect: Revert to previous config if any request fails

When consumers report their bandwidth needs with icc_set_bw(), it's
possible that the requested amount of bandwidth is not available or just
the new configuration fails to apply on some path. In this case revert to
the previous configuration and propagate the error back to the consumers
to let them know that bandwidth is not available, hardware is busy or
whatever error is returned by the interconnect platform driver.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 8091d998549a68ae854f821a2bf0d54d0d694758..6005a1c189f6dfa6be61bea305937a4d3bc5cef3 100644 (file)
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -414,14 +414,18 @@ EXPORT_SYMBOL_GPL(of_icc_get);
 int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
 {
        struct icc_node *node;
+       u32 old_avg, old_peak;
        size_t i;
        int ret;
 
-       if (!path)
+       if (!path || !path->num_nodes)
                return 0;
 
        mutex_lock(&icc_lock);
 
+       old_avg = path->reqs[0].avg_bw;
+       old_peak = path->reqs[0].peak_bw;
+
        for (i = 0; i < path->num_nodes; i++) {
                node = path->reqs[i].node;
 
@@ -434,10 +438,19 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
        }
 
        ret = apply_constraints(path);
-       if (ret)
+       if (ret) {
                pr_debug("interconnect: error applying constraints (%d)\n",
                         ret);
 
+               for (i = 0; i < path->num_nodes; i++) {
+                       node = path->reqs[i].node;
+                       path->reqs[i].avg_bw = old_avg;
+                       path->reqs[i].peak_bw = old_peak;
+                       aggregate_requests(node);
+               }
+               apply_constraints(path);
+       }
+
        mutex_unlock(&icc_lock);
 
        return ret;