The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From a7209541239e5dd44d981289e5f9059222d40fd1 Mon Sep 17 00:00:00 2001 From: Narendra Hadke <nhadke@xxxxxxxxxxx> Date: Tue, 26 Jul 2022 11:12:21 +0200 Subject: [PATCH] serial: mvebu-uart: uart2 error bits clearing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit For mvebu uart2, error bits are not cleared on buffer read. This causes interrupt loop and system hang. Cc: stable@xxxxxxxxxxxxxxx Reviewed-by: Yi Guo <yi.guo@xxxxxxxxxx> Reviewed-by: Nadav Haklai <nadavh@xxxxxxxxxxx> Signed-off-by: Narendra Hadke <nhadke@xxxxxxxxxxx> Signed-off-by: Pali Rohár <pali@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220726091221.12358-1-pali@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> 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);
