linux-kernel - [PATCH 2/4] mailbox: sprd: clear delivery flag before handling TX done

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Message-Id: <20260110-ums9230-mailbox-v1-2-5941cab4f4e5@abscue.de>
Date: Sat, 10 Jan 2026 16:43:36 +0100
From: Otto Pflüger <otto.pflueger@...cue.de>
To: Jassi Brar <jassisinghbrar@...il.com>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Orson Zhai <orsonzhai@...il.com>, 
 Baolin Wang <baolin.wang@...ux.alibaba.com>, 
 Chunyan Zhang <zhang.lyra@...il.com>
Cc: linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 Otto Pflüger <otto.pflueger@...cue.de>
Subject: [PATCH 2/4] mailbox: sprd: clear delivery flag before handling TX
 done

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@...cue.de>
---
 drivers/mailbox/sprd-mailbox.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/mailbox/sprd-mailbox.c b/drivers/mailbox/sprd-mailbox.c
index ee8539dfcef549317f7b86321930bd6bef044598..9a3d388f76b78632ca08948e0fe0ad484aed23c3 100644
--- a/drivers/mailbox/sprd-mailbox.c
+++ b/drivers/mailbox/sprd-mailbox.c
@@ -166,6 +166,11 @@ 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);
@@ -181,11 +186,6 @@ 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);
 

-- 
2.50.0