This reverts commit f45709df7731ad36306a28a3e1af7309d55c35f5.
The `serial8250_do_set_mctrl` not only used by userspace ioctl but
also the kernel itself.
During tty_open, the uart_port_startup sets the MCR to 0, and then use
set_mctrl to restore the MCR, so at this time, the MCR read does not
reflect the desired value.
Signed-off-by: Su Bao Cheng <baocheng.su@xxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_port.c | 7 -------
1 file changed, 7 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 66374704747e..40736e460956 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2024,13 +2024,6 @@ void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl)
struct uart_8250_port *up = up_to_u8250p(port);
unsigned char mcr;
- if (port->rs485.flags & SER_RS485_ENABLED) {
- if (serial8250_in_MCR(up) & UART_MCR_RTS)
- mctrl |= TIOCM_RTS;
- else
- mctrl &= ~TIOCM_RTS;
- }
-
mcr = serial8250_TIOCM_to_MCR(mctrl);
mcr = (mcr & up->mcr_mask) | up->mcr_force | up->mcr;
--
2.25.1
