mailbox: sprd: clear delivery flag before handling TX done

[ Upstream commit c77661d ]

If there are any pending messages in the mailbox queue, they are sent
as soon as a TX done event arrives from the driver. This may trigger a
new delivery interrupt while the previous one is still being handled.
If the delivery status is cleared after this, the interrupt is lost.
To prevent this from happening, clear the delivery status immediately
after checking it and before any new messages are sent.

Signed-off-by: Otto Pflüger <otto.pflueger@abscue.de>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: affenull2345

drivers/mailbox/sprd-mailbox.c

@@ -167,6 +167,11 @@ static irqreturn_t sprd_mbox_inbox_isr(int irq, void *data)
 		return IRQ_NONE;
 	}
 
+	/* Clear FIFO delivery and overflow status first */
+	writel(fifo_sts &
+	       (SPRD_INBOX_FIFO_DELIVER_MASK | SPRD_INBOX_FIFO_OVERLOW_MASK),
+	       priv->inbox_base + SPRD_MBOX_FIFO_RST);
+
 	while (send_sts) {
 		id = __ffs(send_sts);
 		send_sts &= (send_sts - 1);
@@ -182,11 +187,6 @@ static irqreturn_t sprd_mbox_inbox_isr(int irq, void *data)
 			mbox_chan_txdone(chan, 0);
 	}
 
-	/* Clear FIFO delivery and overflow status */
-	writel(fifo_sts &
-	       (SPRD_INBOX_FIFO_DELIVER_MASK | SPRD_INBOX_FIFO_OVERLOW_MASK),
-	       priv->inbox_base + SPRD_MBOX_FIFO_RST);
-
 	/* Clear irq status */
 	writel(SPRD_MBOX_IRQ_CLR, priv->inbox_base + SPRD_MBOX_IRQ_STS);