In dapm_widget_power_read_file(), there is first:

list_for_each_entry(p, &w->sources, list_sink) { if (p->connected && !p->connected(w, p->sink)) continue;

then right after that:

list_for_each_entry(p, &w->sinks, list_source) { if (p->connected && !p->connected(w, p->sink)) continue;

Should that last call to p->connected() be p->connected(p->source, w), since the function's parameters are (source, sink)?