events: Rework event subsystem (add_event, send_event) to be more versatile.

add_event_ex is added that takes an extra user_data pointer. This pointer is
passed to the callback (add_event and add_event_ex have slightly different
callbacks types). All callbacks also get the event id passed. Events added
with add_event_ex must be removed with remove_event_ex because the user_data
pointer must match in addition to the callback pointer.

On the other add_event is simplified to omit the oneshort parameter which
was almost always false (still there with add_event_ex).

As a side effect the ata_idle_notify callbacks are changed as well, they
do not take a data parameter anymore which was always NULL anyway.

This commit also adds some documentation to events.h

Change-Id: I13e29a0f88ef908f175b376d83550f9e0231f772

1 files changed, 1 insertions, 2 deletions

diff --git a/apps/playlist.c b/apps/playlist.c
index 0e73781238..a066dd2ea0 100755
--- a/apps/playlist.c
+++ b/apps/playlist.c
@@ -1223,9 +1223,8 @@ static int compare(const void* p1, const void* p2)
  * without affecting playlist load up performance.  This thread also flushes
  * any pending control commands when the disk spins up.
  */
-static void playlist_flush_callback(void *param)
+static void playlist_flush_callback(void)
 {
-    (void)param;
     struct playlist_info *playlist;
     playlist = &current_playlist;
     if (playlist->control_fd >= 0)