linux-kernel - [PATCH] serial: mvebu-uart: uart2 error bits clearing

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Message-Id: <20220726091221.12358-1-pali@kernel.org>
Date:   Tue, 26 Jul 2022 11:12:21 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] serial: mvebu-uart: uart2 error bits clearing

From: Narendra Hadke <nhadke@...vell.com>

For mvebu uart2, error bits are not cleared on buffer read.
This causes interrupt loop and system hang.

Signed-off-by: Narendra Hadke <nhadke@...vell.com>
Reviewed-by: Yi Guo <yi.guo@...ium.com>
Reviewed-by: Nadav Haklai <nadavh@...vell.com>
Signed-off-by: Pali Rohár <pali@...nel.org>
Cc: stable@...r.kernel.org
---
 drivers/tty/serial/mvebu-uart.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c
index 0429c2a54290..ff61a8d00014 100644
--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -265,6 +265,7 @@ static void mvebu_uart_rx_chars(struct uart_port *port, unsigned int status)
 	struct tty_port *tport = &port->state->port;
 	unsigned char ch = 0;
 	char flag = 0;
+	int ret;
 
 	do {
 		if (status & STAT_RX_RDY(port)) {
@@ -277,6 +278,16 @@ static void mvebu_uart_rx_chars(struct uart_port *port, unsigned int status)
 				port->icount.parity++;
 		}
 
+		/*
+		 * For UART2, error bits are not cleared on buffer read.
+		 * This causes interrupt loop and system hang.
+		 */
+		if (IS_EXTENDED(port) && (status & STAT_BRK_ERR)) {
+			ret = readl(port->membase + UART_STAT);
+			ret |= STAT_BRK_ERR;
+			writel(ret, port->membase + UART_STAT);
+		}
+
 		if (status & STAT_BRK_DET) {
 			port->icount.brk++;
 			status &= ~(STAT_FRM_ERR | STAT_PAR_ERR);
-- 
2.20.1