From: Su Bao Cheng <baocheng.su@siemens.com>
To: linux-serial@vger.kernel.org, gregkh@linuxfoundation.org,
lukas@wunner.de
Cc: jan.kiszka@siemens.com, chao.zeng@siemens.com,
Su Bao Cheng <baocheng.su@siemens.com>
Subject: [PATCH] Revert "serial: 8250: Don't touch RTS modem control while in rs485 mode"
Date: Wed, 27 Oct 2021 19:16:44 +0800 [thread overview]
Message-ID: <20211027111644.1996921-1-baocheng.su@siemens.com> (raw)
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@siemens.com>
---
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
next reply other threads:[~2021-10-27 11:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-27 11:16 Su Bao Cheng [this message]
2021-10-27 11:39 ` [PATCH] Revert "serial: 8250: Don't touch RTS modem control while in rs485 mode" Lukas Wunner
2021-11-12 6:14 ` Su Bao Cheng
2021-11-19 8:00 ` Jan Kiszka
2021-11-19 8:43 ` Jan Kiszka
2021-11-19 11:17 ` Lukas Wunner
2021-11-19 11:12 ` Lukas Wunner
2021-11-20 17:18 ` Lukas Wunner
2021-11-21 9:00 ` Jan Kiszka
2021-11-21 17:43 ` Lukas Wunner
2021-11-22 9:01 ` Su Bao Cheng
2021-11-22 17:11 ` Lukas Wunner
2021-12-13 16:12 ` Lukas Wunner
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