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

The hardware supports both RTS_ON_SEND and RTS_AFTER_SEND modes, but
after the commit 4afeced55baa ("serial: core: fix sanitizing check for
RTS settings") we always end up with SER_RS485_RTS_AFTER_SEND and
always write in the register field SC16IS7XX_EFCR_RTS_INVERT_BIT, which
breaks some hardware using these chips.

Fixes: 267913ecf737 ("serial: sc16is7xx: Fill in rs485_supported")
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Konstantin Pugin <ria.freelander@gmail.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 929206a9a6e1..a300eebf1401 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1458,7 +1458,7 @@ 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 */
 };
-- 
2.34.1

On Thu, Apr 18, 2024 at 08:06:05PM +0300, Konstantin Pugin wrote:
> From: Konstantin Pugin <ria.freelander@gmail.com>
> 
> The hardware supports both RTS_ON_SEND and RTS_AFTER_SEND modes, but
> after the commit 4afeced55baa ("serial: core: fix sanitizing check for
> RTS settings") we always end up with SER_RS485_RTS_AFTER_SEND and

  "...with _RTS_AFTER_SEND set..."

or

  "...with _RTS_AFTER_SEND clear..."

or?..

> always write in the register field SC16IS7XX_EFCR_RTS_INVERT_BIT, which

write to

> breaks some hardware using these chips.

...

I might have been not clear about Vladimir's tag. Please double check
if he gave it against the certain patch or the entire series.

-- 
With Best Regards,
Andy Shevchenko