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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Yi Guo <yi.guo@cavium.com>,
        Nadav Haklai <nadavh@marvell.com>,
        Narendra Hadke <nhadke@marvell.com>,
        =?UTF-8?q?Pali=20Roh=C3=A1r?= <pali@kernel.org>
Subject: [PATCH 5.15 087/779] serial: mvebu-uart: uart2 error bits clearing
Date:   Mon, 15 Aug 2022 19:55:31 +0200
Message-Id: <20220815180340.999276684@linuxfoundation.org>
In-Reply-To: <20220815180337.130757997@linuxfoundation.org>
References: <20220815180337.130757997@linuxfoundation.org>
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From: Narendra Hadke <nhadke@marvell.com>

commit a7209541239e5dd44d981289e5f9059222d40fd1 upstream.

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

Cc: stable@vger.kernel.org
Reviewed-by: Yi Guo <yi.guo@cavium.com>
Reviewed-by: Nadav Haklai <nadavh@marvell.com>
Signed-off-by: Narendra Hadke <nhadke@marvell.com>
Signed-off-by: Pali Rohár <pali@kernel.org>
Link: https://lore.kernel.org/r/20220726091221.12358-1-pali@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/mvebu-uart.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -237,6 +237,7 @@ static void mvebu_uart_rx_chars(struct u
 	struct tty_port *tport = &port->state->port;
 	unsigned char ch = 0;
 	char flag = 0;
+	int ret;
 
 	do {
 		if (status & STAT_RX_RDY(port)) {
@@ -249,6 +250,16 @@ static void mvebu_uart_rx_chars(struct u
 				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);