linux-kernel - Re: [PATCH v4 1/3] serial: sc16is7xx: announce support of SER_RS485_RTS_ON

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Message-Id: <20240419092952.e458f83d8b414b178d598c19@hugovil.com>
Date: Fri, 19 Apr 2024 09:29:52 -0400
From: Hugo Villeneuve <hugo@...ovil.com>
To: Konstantin Pugin <rilian.la.te@...ru>
Cc: Konstantin Pugin <ria.freelander@...il.com>, Greg Kroah-Hartman
 <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>, Hugo
 Villeneuve <hvilleneuve@...onoff.com>, Andy Shevchenko
 <andriy.shevchenko@...ux.intel.com>, Lech Perczak
 <lech.perczak@...lingroup.com>, Ilpo Järvinen
 <ilpo.jarvinen@...ux.intel.com>, Thomas Gleixner <tglx@...utronix.de>,
 linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH v4 1/3] serial: sc16is7xx: announce support of
 SER_RS485_RTS_ON_SEND

On Fri, 19 Apr 2024 15:45:01 +0300
Konstantin Pugin <rilian.la.te@...ru> wrote:

> From: Konstantin Pugin <ria.freelander@...il.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 set and
> always write to the register field SC16IS7XX_EFCR_RTS_INVERT_BIT, which
> breaks some hardware using these chips.

Hi Konstantin,
I am using RS-485 mode, and currently I may need SC16IS7XX_EFCR_RTS_INVERT_BIT to be set for my setup to work (not sure, must check this). Does it mean that with this patch it will be cleared? I am not sure by reading your commit message...

I need to look at this in more details, and test it on my hardware, which I will be able to do only next week. I will keep you posted.

Hugo.



> 
> Fixes: 267913ecf737 ("serial: sc16is7xx: Fill in rs485_supported")
> 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 */
>  };
> -- 
> 2.34.1
> 
> 
> 


-- 
Hugo Villeneuve <hugo@...ovil.com>