linux-kernel - [PATCH] serial: pl011: Do not clear RX FIFO & RX interrupt in unthrottle.

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Message-Id: <20221110020108.7700-1-delisun@pateo.com.cn>
Date:   Thu, 10 Nov 2022 10:01:08 +0800
From:   delisun <delisun@...eo.com.cn>
To:     linux@...linux.org.uk
Cc:     gregkh@...uxfoundation.org, jirislaby@...nel.org,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        delisun <delisun@...eo.com.cn>
Subject: [PATCH] serial: pl011: Do not clear RX FIFO & RX interrupt in unthrottle.

Clearing the RX FIFO will cause data loss.
Copy the pl011_enabl_interrupts implementation, and remove the clear
interrupt and FIFO part of the code.

Fixes: 211565b10099 ("serial: pl011: UPSTAT_AUTORTS requires .throttle/unthrottle")
Signed-off-by: delisun <delisun@...eo.com.cn>
---
 drivers/tty/serial/amba-pl011.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 5cdced39eafd..08034e5dcec0 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1828,8 +1828,17 @@ static void pl011_enable_interrupts(struct uart_amba_port *uap)
 static void pl011_unthrottle_rx(struct uart_port *port)
 {
 	struct uart_amba_port *uap = container_of(port, struct uart_amba_port, port);
+	unsigned long flags;
 
-	pl011_enable_interrupts(uap);
+	spin_lock_irqsave(&uap->port.lock, flags);
+
+	uap->im = UART011_RTIM;
+	if (!pl011_dma_rx_running(uap))
+		uap->im |= UART011_RXIM;
+
+	pl011_write(uap->im, uap, REG_IMSC);
+
+	spin_unlock_irqrestore(&uap->port.lock, flags);
 }
 
 static int pl011_startup(struct uart_port *port)
-- 
2.25.1