From 032d5a71ed378ffc6a2d41a187d8488a4f9fe415 Mon Sep 17 00:00:00 2001
From: delisun <delisun@pateo.com.cn>
Date: Thu, 10 Nov 2022 10:01:08 +0800
Subject: [PATCH] serial: pl011: Do not clear RX FIFO & RX interrupt in unthrottle.
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Git-commit: 032d5a71ed378ffc6a2d41a187d8488a4f9fe415
Patch-mainline: v6.2-rc1
References: git-fixes

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@pateo.com.cn>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221110020108.7700-1-delisun@pateo.com.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 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 6b9deb4211b5..d75c39f4622b 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1830,8 +1830,17 @@ 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)
-- 
2.35.3