linux-kernel - [PATCH v8 1/3] serial: sc16is7xx: announce support of SER_RS485_RTS_ON

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Date: Wed, 24 Apr 2024 22:18:52 +0300
From: Konstantin Pugin <rilian.la.te@...ru>
To: 
Cc: krzk@...nel.org,
	conor@...nel.org,
	lkp@...el.com,
	vz@...ia.com,
	robh@...nel.org,
	jcmvbkbc@...il.com,
	nicolas.ferre@...rochip.com,
	manikanta.guntupalli@....com,
	corbet@....net,
	ychuang3@...oton.com,
	u.kleine-koenig@...gutronix.de,
	Maarten.Brock@...ls.nl,
	Konstantin Pugin <ria.freelander@...il.com>,
	Hugo Villeneuve <hvilleneuve@...onoff.com>,
	Andy Shevchenko <andy@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Lech Perczak <lech.perczak@...lingroup.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org
Subject: [PATCH v8 1/3] serial: sc16is7xx: announce support of SER_RS485_RTS_ON_SEND

From: Konstantin Pugin <ria.freelander@...il.com>

When specifying flag SER_RS485_RTS_ON_SEND in RS485 configuration,
we get the following warning after commit 4afeced55baa ("serial: core:
fix sanitizing check for RTS settings"):

    invalid RTS setting, using RTS_AFTER_SEND instead

This results in SER_RS485_RTS_AFTER_SEND being set and the
driver always write to the register field SC16IS7XX_EFCR_RTS_INVERT_BIT,
which breaks some hardware using these chips.

The hardware supports both RTS_ON_SEND and RTS_AFTER_SEND modes, so fix
this by announcing support for RTS_ON_SEND.

Fixes: 267913ecf737 ("serial: sc16is7xx: Fill in rs485_supported")
Tested-by: Hugo Villeneuve <hvilleneuve@...onoff.com>
Reviewed-by: Andy Shevchenko <andy@...nel.org>
Signed-off-by: Konstantin Pugin <ria.freelander@...il.com>
---
 drivers/tty/serial/sc16is7xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 03cf30e20b75..dfcc804f558f 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1449,7 +1449,7 @@ static int sc16is7xx_setup_mctrl_ports(struct sc16is7xx_port *s,
 }
 
 static const struct serial_rs485 sc16is7xx_rs485_supported = {
-	.flags = SER_RS485_ENABLED | SER_RS485_RTS_AFTER_SEND,
+	.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RTS_AFTER_SEND,
 	.delay_rts_before_send = 1,
 	.delay_rts_after_send = 1,	/* Not supported but keep returning -EINVAL */
 };
-- 
2.44.0