[PATCH 6.18 316/752] mailbox: sprd: clear delivery flag before handling TX done

Sasha Levin
2026-02-28T17:52:33Z

From: Otto Pflüger <otto.pflueger@abscue.de>

[ Upstream commit c77661d60d4223bf2ff10d409beb0c3b2021183b ]

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>
---
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 c1a5fe6cc8771..46d0c34177ab9 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);

--
2.51.0