--- zzzz-none-000/linux-4.4.60/drivers/mailbox/mailbox.c	2017-04-08 07:53:53.000000000 +0000
+++ scorpion-7490-727/linux-4.4.60/drivers/mailbox/mailbox.c	2021-02-04 17:41:59.000000000 +0000
@@ -87,8 +87,7 @@
 
 	if (!err && (chan->txdone_method & TXDONE_BY_POLL))
 		/* kick start the timer immediately to avoid delays */
-		hrtimer_start(&chan->mbox->poll_hrt, ktime_set(0, 0),
-			      HRTIMER_MODE_REL);
+		hrtimer_start(&chan->mbox->poll_hrt, ktime_set(0, 0), HRTIMER_MODE_REL);
 }
 
 static void tx_tick(struct mbox_chan *chan, int r)
@@ -104,11 +103,14 @@
 	/* 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 (chan->cl->tx_block)
+	if (r != -ETIME && chan->cl->tx_block)
 		complete(&chan->tx_complete);
 }
 
@@ -261,7 +263,7 @@
 
 	msg_submit(chan);
 
-	if (chan->cl->tx_block && chan->active_req) {
+	if (chan->cl->tx_block) {
 		unsigned long wait;
 		int ret;
 
@@ -272,8 +274,8 @@
 
 		ret = wait_for_completion_timeout(&chan->tx_complete, wait);
 		if (ret == 0) {
-			t = -EIO;
-			tx_tick(chan, -EIO);
+			t = -ETIME;
+			tx_tick(chan, t);
 		}
 	}
 
@@ -349,15 +351,18 @@
 	init_completion(&chan->tx_complete);
 
 	if (chan->txdone_method	== TXDONE_BY_POLL && cl->knows_txdone)
-		chan->txdone_method |= TXDONE_BY_ACK;
+		chan->txdone_method = TXDONE_BY_ACK;
 
 	spin_unlock_irqrestore(&chan->lock, flags);
 
-	ret = chan->mbox->ops->startup(chan);
-	if (ret) {
-		dev_err(dev, "Unable to startup the chan (%d)\n", ret);
-		mbox_free_channel(chan);
-		chan = ERR_PTR(ret);
+	if (chan->mbox->ops->startup) {
+		ret = chan->mbox->ops->startup(chan);
+
+		if (ret) {
+			dev_err(dev, "Unable to startup the chan (%d)\n", ret);
+			mbox_free_channel(chan);
+			chan = ERR_PTR(ret);
+		}
 	}
 
 	mutex_unlock(&con_mutex);
@@ -375,13 +380,13 @@
 
 	if (!np) {
 		dev_err(cl->dev, "%s() currently only supports DT\n", __func__);
-		return ERR_PTR(-ENOSYS);
+		return ERR_PTR(-EINVAL);
 	}
 
 	if (!of_get_property(np, "mbox-names", NULL)) {
 		dev_err(cl->dev,
 			"%s() requires an \"mbox-names\" property\n", __func__);
-		return ERR_PTR(-ENOSYS);
+		return ERR_PTR(-EINVAL);
 	}
 
 	of_property_for_each_string(np, "mbox-names", prop, mbox_name) {
@@ -406,13 +411,14 @@
 	if (!chan || !chan->cl)
 		return;
 
-	chan->mbox->ops->shutdown(chan);
+	if (chan->mbox->ops->shutdown)
+		chan->mbox->ops->shutdown(chan);
 
 	/* The queued TX requests are simply aborted, no callbacks are made */
 	spin_lock_irqsave(&chan->lock, flags);
 	chan->cl = NULL;
 	chan->active_req = NULL;
-	if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
+	if (chan->txdone_method == TXDONE_BY_ACK)
 		chan->txdone_method = TXDONE_BY_POLL;
 
 	module_put(chan->mbox->dev->driver->owner);
@@ -454,6 +460,12 @@
 		txdone = TXDONE_BY_ACK;
 
 	if (txdone == TXDONE_BY_POLL) {
+
+		if (!mbox->ops->last_tx_done) {
+			dev_err(mbox->dev, "last_tx_done method is absent\n");
+			return -EINVAL;
+		}
+
 		hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,
 			     HRTIMER_MODE_REL);
 		mbox->poll_hrt.function = txdone_hrtimer;