linux-kernel - [PATCH 1/7] serial: 8250: Make em485_rts_after_send() set mctrl according to rts state.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 18 Mar 2020 15:26:34 +0100
From:   Heiko Stuebner <heiko@...ech.de>
To:     gregkh@...uxfoundation.org
Cc:     jslaby@...e.com, andriy.shevchenko@...ux.intel.com,
        matwey.kornilov@...il.com, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org, heiko@...ech.de,
        Giulio Benetti <giulio.benetti@...ronovasrl.com>,
        Heiko Stuebner <heiko.stuebner@...obroma-systems.com>
Subject: [PATCH 1/7] serial: 8250: Make em485_rts_after_send() set mctrl according to rts state.

From: Giulio Benetti <giulio.benetti@...ronovasrl.com>

When rs485 enabled and RTS_AFTER_SEND set on startup, need to preserve
mctrl status, because later functions will call set_mctrl passing
port->mctrl=0 overriding rts status, resulting in rts pin in
transmission when idle.

Make mctrl reflect rts pin state.

Signed-off-by: Giulio Benetti <giulio.benetti@...ronovasrl.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@...obroma-systems.com>
---
 drivers/tty/serial/8250/8250_port.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 8407166610ce..67aa3a2a9afa 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -565,10 +565,13 @@ static inline void serial8250_em485_rts_after_send(struct uart_8250_port *p)
 {
 	unsigned char mcr = serial8250_in_MCR(p);
 
-	if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
+	if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND) {
 		mcr |= UART_MCR_RTS;
-	else
+		p->port.mctrl |= TIOCM_RTS;
+	} else {
 		mcr &= ~UART_MCR_RTS;
+		p->port.mctrl &= ~TIOCM_RTS;
+	}
 	serial8250_out_MCR(p, mcr);
 }
 
-- 
2.24.1