[PATCH 3/3] mailbox: handle empty message in tx_tick

[Sudeep Holla <sudeep.holla@arm.com>]

We already check if the message is empty before calling the client
tx_done callback. Calling completion on a wait event is also invalid
if the message is empty.

This patch moves the existing empty message check earlier.

Fixes: 2b6d83e2b8b7 ("mailbox: Introduce framework for mailbox")
Cc: Jassi Brar <jassisinghbrar@gmail.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/mailbox/mailbox.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 2ed7fa681ecb..5ef014241212 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -103,8 +103,11 @@ static void tx_tick(struct mbox_chan *chan, int r)
 	/* Submit next message */
 	msg_submit(chan);
 
+	if (!mssg)
+		return;
+
 	/* Notify the client */
-	if (mssg && chan->cl->tx_done)
+	if (chan->cl->tx_done)
 		chan->cl->tx_done(chan->cl, mssg, r);
 
 	if (r != -ETIME && chan->cl->tx_block)
-- 
2.7.4