[PATCH 5.4 036/389] serial: mvebu-uart: uart2 error bits clearing

Greg Kroah-Hartman
2022-08-23T11:28:43Z

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
@@ -238,6 +238,7 @@ 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)) {
@@ -250,6 +251,16 @@ 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);