mmal/deinterlace: Implement filter flush

It is required to flush the filter properly for stopping of playback to work
reliably. Without flushing the code might detect pictures currently held in
the filter as lost which will lead to double frees later on.
Signed-off-by: Julian Scheel <julian@jusst.de>
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

modules/hw/mmal/deinterlace.c

@@ -66,15 +66,18 @@ struct filter_sys_t {
 
     MMAL_QUEUE_T *filtered_pictures;
     vlc_mutex_t mutex;
+    vlc_cond_t buffer_cond;
 
     /* statistics */
     int output_in_transit;
+    int input_in_transit;
 };
 
 static void control_port_cb(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer);
 static void input_port_cb(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer);
 static void output_port_cb(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer);
 static picture_t *deinterlace(filter_t *filter, picture_t *picture);
+static void flush(filter_t *filter);
 
 #define MMAL_COMPONENT_DEFAULT_DEINTERLACE "vc.ril.image_fx"
 
@@ -278,7 +281,9 @@ static int Open(filter_t *filter)
         goto out;
 
     filter->pf_video_filter = deinterlace;
+    filter->pf_video_flush = flush;
     vlc_mutex_init_recursive(&sys->mutex);
+    vlc_cond_init(&sys->buffer_cond);
 
 out:
     if (ret != VLC_SUCCESS)
@@ -333,6 +338,7 @@ static void Close(filter_t *filter)
         picture_pool_Release(sys->picture_pool);
 
     vlc_mutex_destroy(&sys->mutex);
+    vlc_cond_destroy(&sys->buffer_cond);
     free(sys->pictures);
     free(sys);
 
@@ -455,12 +461,41 @@ static picture_t *deinterlace(filter_t *filter, picture_t *picture)
         msg_Err(filter, "Failed to send buffer to input port (status=%"PRIx32" %s)",
                 status, mmal_status_to_string(status));
     }
+    sys->input_in_transit++;
 
 out:
     vlc_mutex_unlock(&sys->mutex);
     return ret;
 }
 
+static void flush(filter_t *filter)
+{
+    filter_sys_t *sys = filter->p_sys;
+    MMAL_STATUS_T status;
+
+    mmal_port_disable(sys->output);
+    mmal_port_disable(sys->input);
+    mmal_port_flush(sys->output);
+    mmal_port_flush(sys->input);
+    status = mmal_port_enable(sys->input, input_port_cb);
+    if (status != MMAL_SUCCESS) {
+        msg_Err(filter, "Failed to enable input port %s (status=%"PRIx32" %s)",
+                sys->input->name, status, mmal_status_to_string(status));
+        return;
+    }
+    status = mmal_port_enable(sys->output, output_port_cb);
+    if (status != MMAL_SUCCESS) {
+        msg_Err(filter, "Failed to enable output port %s (status=%"PRIx32" %s)",
+                sys->output->name, status, mmal_status_to_string(status));
+    }
+
+    msg_Dbg(filter, "flush: wait for all buffers to be returned");
+    vlc_mutex_lock(&sys->mutex);
+    while (sys->input_in_transit || sys->output_in_transit)
+        vlc_cond_wait(&sys->buffer_cond, &sys->mutex);
+    vlc_mutex_unlock(&sys->mutex);
+}
+
 static void control_port_cb(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
 {
     filter_t *filter = (filter_t *)port->userdata;
@@ -486,6 +521,8 @@ static void input_port_cb(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
     mmal_buffer_header_release(buffer);
     if (picture)
         picture_Release(picture);
+    sys->input_in_transit--;
+    vlc_cond_signal(&sys->buffer_cond);
     vlc_mutex_unlock(&sys->mutex);
 }
 
@@ -506,6 +543,7 @@ static void output_port_cb(MMAL_PORT_T *port, MMAL_BUFFER_HEADER_T *buffer)
             buffer->user_data = NULL;
         }
         sys->output_in_transit--;
+        vlc_cond_signal(&sys->buffer_cond);
     } else if (buffer->cmd == MMAL_EVENT_FORMAT_CHANGED) {
         msg_Warn(filter, "MMAL_EVENT_FORMAT_CHANGED seen but not handled");
         mmal_buffer_header_release(buffer);