drivers/rpmsg_port: notify the lower transport when no free buffers

When no free buffers, notify the lower transport, so the lower
transports can know this thing and do some work, such as continue
to process the rx data to avoid the rx thread is blocked that
even can't process the commands.

Signed-off-by: Bowen Wang <wangbowen6@xiaomi.com>
Signed-off-by: liaoao <liaoao@xiaomi.com>

drivers/rpmsg/rpmsg_port.c

@@ -215,6 +215,8 @@ rpmsg_port_create_queues(FAR struct rpmsg_port_s *port,
       return ret;
     }
 
+  port->txq.port = port;
+  port->rxq.port = port;
   return 0;
 }
 
@@ -608,8 +610,10 @@ FAR struct rpmsg_port_header_s *
 rpmsg_port_queue_get_available_buffer(FAR struct rpmsg_port_queue_s *queue,
                                       bool wait)
 {
-  FAR struct list_node *node;
+  FAR struct rpmsg_port_s *port = queue->port;
   FAR struct rpmsg_port_header_s *hdr;
+  FAR struct list_node *node;
+  int ret;
 
   for (; ; )
     {
@@ -625,7 +629,12 @@ rpmsg_port_queue_get_available_buffer(FAR struct rpmsg_port_queue_s *queue,
           return NULL;
         }
 
-      nxsem_wait_uninterruptible(&queue->free.sem);
+      ret = port->ops->notify_queue_noavail ?
+            port->ops->notify_queue_noavail(port, queue) : -ENOTSUP;
+      if (ret == -ENOTSUP)
+        {
+          nxsem_wait_uninterruptible(&queue->free.sem);
+        }
     }
 }
 

drivers/rpmsg/rpmsg_port.h

@@ -67,8 +67,14 @@ struct rpmsg_port_list_s
   struct list_node head;          /* List head */
 };
 
+struct rpmsg_port_s;
+
 struct rpmsg_port_queue_s
 {
+  /* Pointer to the rpmsg port handler */
+
+  FAR struct rpmsg_port_s  *port;
+
   /* Indicate buffers current queue managed is dynamic alloced */
 
   bool                     alloced;
@@ -94,8 +100,6 @@ struct rpmsg_port_queue_s
   struct rpmsg_port_list_s ready;
 };
 
-struct rpmsg_port_s;
-
 typedef void (*rpmsg_port_rx_cb_t)(FAR struct rpmsg_port_s *port,
                                    FAR struct rpmsg_port_header_s *hdr);
 
@@ -109,6 +113,11 @@ struct rpmsg_port_ops_s
 
   CODE void (*notify_rx_free)(FAR struct rpmsg_port_s *port);
 
+  /* Notify driver there is no available buffer */
+
+  CODE int (*notify_queue_noavail)(FAR struct rpmsg_port_s *port,
+                                   FAR struct rpmsg_port_queue_s *queue);
+
   /* Register callback function which should be invoked when there is
    * date received to the rx queue by driver
    */

drivers/rpmsg/rpmsg_port_spi.c

@@ -140,6 +140,7 @@ static const struct rpmsg_port_ops_s g_rpmsg_port_spi_ops =
 {
   rpmsg_port_spi_notify_tx_ready,
   rpmsg_port_spi_notify_rx_free,
+  NULL,
   rpmsg_port_spi_register_cb,
 };
 

drivers/rpmsg/rpmsg_port_spi_slave.c

@@ -158,6 +158,7 @@ static const struct rpmsg_port_ops_s g_rpmsg_port_spi_ops =
 {
   rpmsg_port_spi_notify_tx_ready,
   rpmsg_port_spi_notify_rx_free,
+  NULL,
   rpmsg_port_spi_register_cb,
 };