From: Narendra Hadke <nhadke@xxxxxxxxxxx> commit a7209541239e5dd44d981289e5f9059222d40fd1 upstream. 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> --- 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);
