mmal: Replace global mutex by module-owned mutex

The mutex held within mmal_pictures is used to lock access of mmal
picture/buffer pools between vlc main thread and mmal callback threads. This
is only required to be locked per pool and not globally for all mmal modules.
Thus using a global mutex caused a slight performance hit when using mmal vout
and deinterlace simultaneously which operate on independent picture pools. Now
the pool owner provides the mutex handle when allocating the pictures, so
that independent locking can be used.
Signed-off-by: Julian Scheel <julian@jusst.de>
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

modules/hw/mmal/deinterlace.c

@@ -98,6 +98,7 @@ static int create_picture_pool(filter_t *filter)
 
         picture_res.p_sys->owner = (vlc_object_t *)filter;
         picture_res.p_sys->queue = sys->output_pool->queue;
+        picture_res.p_sys->mutex = &sys->mutex;
 
         sys->pictures[i] = picture_NewFromResource(&filter->fmt_out.video,
                 &picture_res);

modules/hw/mmal/mmal_picture.c

@@ -27,18 +27,12 @@
 
 #include "mmal_picture.h"
 
-vlc_mutex_t* get_mmal_opaque_mutex(void)
-{
-    static vlc_mutex_t mmal_mutex = VLC_STATIC_MUTEX;
-    return &mmal_mutex;
-}
-
 int mmal_picture_lock(picture_t *picture)
 {
     picture_sys_t *pic_sys = picture->p_sys;
     int ret = VLC_SUCCESS;
 
-    vlc_mutex_lock(get_mmal_opaque_mutex());
+    vlc_mutex_lock(pic_sys->mutex);
 
     MMAL_BUFFER_HEADER_T *buffer = mmal_queue_timedwait(pic_sys->queue, 2);
     if (!buffer) {
@@ -57,7 +51,7 @@ int mmal_picture_lock(picture_t *picture)
     pic_sys->displayed = false;
 
 out:
-    vlc_mutex_unlock(get_mmal_opaque_mutex());
+    vlc_mutex_unlock(pic_sys->mutex);
     return ret;
 }
 
@@ -66,7 +60,7 @@ void mmal_picture_unlock(picture_t *picture)
     picture_sys_t *pic_sys = picture->p_sys;
     MMAL_BUFFER_HEADER_T *buffer = pic_sys->buffer;
 
-    vlc_mutex_lock(get_mmal_opaque_mutex());
+    vlc_mutex_lock(pic_sys->mutex);
 
     pic_sys->buffer = NULL;
     if (buffer) {
@@ -74,5 +68,5 @@ void mmal_picture_unlock(picture_t *picture)
         mmal_buffer_header_release(buffer);
     }
 
-    vlc_mutex_unlock(get_mmal_opaque_mutex());
+    vlc_mutex_unlock(pic_sys->mutex);
 }

modules/hw/mmal/mmal_picture.h

@@ -32,6 +32,7 @@ struct picture_sys_t {
 
     MMAL_BUFFER_HEADER_T *buffer;
     MMAL_QUEUE_T *queue;
+    vlc_mutex_t *mutex;
     bool displayed;
 };
 

modules/hw/mmal/vout.c

@@ -498,6 +498,7 @@ static picture_pool_t *vd_pool(vout_display_t *vd, unsigned count)
         picture_res.p_sys = calloc(1, sizeof(picture_sys_t));
         picture_res.p_sys->owner = (vlc_object_t *)vd;
         picture_res.p_sys->queue = sys->pool->queue;
+        picture_res.p_sys->mutex = &sys->buffer_mutex;
 
         sys->pictures[i] = picture_NewFromResource(&fmt, &picture_res);
         if (!sys->pictures[i]) {