greybus: connection: add flush host-device callback

Add a new host-device callback to flush any host-device queues,
including any ongoing transfers, as part of connection tear down.

The host-device buffers are flushed after the disconnecting operation
have completed and the AP queues have been emptied.

This can be used to flush already queued messages which upon reception
would have been discarded by the remote end anyway.

Note that this does not remove the need to flush any host-device queues
as part of CPort disable which needs to make the CPort ready for reuse
after deallocating all associated state and resetting the port.

Suggested-by: Mitchell Tasman <tasman@leaflabs.com>
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/connection.c b/drivers/staging/greybus/connection.c
index 77067515a28a3e91d3b45246d05662d582123e2e..c1cdfcd830a48be1d3cdbb5e8ae5f592bc33c594 100644 (file)
--- a/drivers/staging/greybus/connection.c
+++ b/drivers/staging/greybus/connection.c
@@ -302,6 +302,24 @@ static void gb_connection_hd_cport_disable(struct gb_connection *connection)
        }
 }
 
+static int gb_connection_hd_cport_flush(struct gb_connection *connection)
+{
+       struct gb_host_device *hd = connection->hd;
+       int ret;
+
+       if (!hd->driver->cport_flush)
+               return 0;
+
+       ret = hd->driver->cport_flush(hd, connection->hd_cport_id);
+       if (ret) {
+               dev_err(&hd->dev, "%s: failed to flush host cport: %d\n",
+                               connection->name, ret);
+               return ret;
+       }
+
+       return 0;
+}
+
 static int
 gb_connection_hd_cport_features_enable(struct gb_connection *connection)
 {
@@ -651,6 +669,9 @@ err_control_disconnecting:
        gb_connection_cancel_operations(connection, -ESHUTDOWN);
        spin_unlock_irq(&connection->lock);
 
+       /* Transmit queue should already be empty. */
+       gb_connection_hd_cport_flush(connection);
+
        gb_connection_ping(connection);
        gb_connection_hd_cport_features_disable(connection);
        gb_connection_svc_connection_quiescing(connection);
@@ -736,6 +757,8 @@ void gb_connection_disable(struct gb_connection *connection)
        gb_connection_cancel_operations(connection, -ESHUTDOWN);
        spin_unlock_irq(&connection->lock);
 
+       gb_connection_hd_cport_flush(connection);
+
        gb_connection_ping(connection);
        gb_connection_hd_cport_features_disable(connection);
        gb_connection_svc_connection_quiescing(connection);
@@ -766,6 +789,7 @@ void gb_connection_disable_forced(struct gb_connection *connection)
        gb_connection_cancel_operations(connection, -ESHUTDOWN);
        spin_unlock_irq(&connection->lock);
 
+       gb_connection_hd_cport_flush(connection);
        gb_connection_hd_cport_features_disable(connection);
        gb_connection_svc_connection_destroy(connection);
        gb_connection_hd_cport_disable(connection);

diff --git a/drivers/staging/greybus/hd.h b/drivers/staging/greybus/hd.h
index 7321cfdd41d7dad891468024b51e3633b6708f60..5136d0c9ecc802cb1a19da8a3cb1817970a86086 100644 (file)
--- a/drivers/staging/greybus/hd.h
+++ b/drivers/staging/greybus/hd.h
@@ -21,6 +21,7 @@ struct gb_hd_driver {
        void (*cport_release)(struct gb_host_device *hd, u16 cport_id);
        int (*cport_enable)(struct gb_host_device *hd, u16 cport_id);
        int (*cport_disable)(struct gb_host_device *hd, u16 cport_id);
+       int (*cport_flush)(struct gb_host_device *hd, u16 cport_id);
        int (*cport_ping)(struct gb_host_device *hd, u16 cport_id);
        int (*message_send)(struct gb_host_device *hd, u16 dest_cport_id,
                        struct gb_message *message, gfp_t gfp_mask);