Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 0b821a5..3e7d4b2 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -82,9 +82,12 @@
 exit:
 	spin_unlock_irqrestore(&chan->lock, flags);
 
-	if (!err && (chan->txdone_method & TXDONE_BY_POLL))
-		/* kick start the timer immediately to avoid delays */
-		hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
+	/* kick start the timer immediately to avoid delays */
+	if (!err && (chan->txdone_method & TXDONE_BY_POLL)) {
+		/* but only if not already active */
+		if (!hrtimer_active(&chan->mbox->poll_hrt))
+			hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
+	}
 }
 
 static void tx_tick(struct mbox_chan *chan, int r)
@@ -122,11 +125,10 @@
 		struct mbox_chan *chan = &mbox->chans[i];
 
 		if (chan->active_req && chan->cl) {
+			resched = true;
 			txdone = chan->mbox->ops->last_tx_done(chan);
 			if (txdone)
 				tx_tick(chan, 0);
-			else
-				resched = true;
 		}
 	}