linux-kernel - Re: [PATCH 1/7] serial: 8250_dwlib: RS485 HW half duplex support

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Message-ID: <d9aabfe-1179-67c2-98d1-f36e7e698f33@linux.intel.com>
Date:   Tue, 8 Mar 2022 14:59:59 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Lukas Wunner <lukas@...ner.de>
cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Johan Hovold <johan@...nel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Raymond Tan <raymond.tan@...el.com>,
        Heiko Stuebner <heiko@...ech.de>
Subject: Re: [PATCH 1/7] serial: 8250_dwlib: RS485 HW half duplex support

On Tue, 8 Mar 2022, Lukas Wunner wrote:

> On Tue, Mar 08, 2022 at 02:16:56PM +0200, Ilpo Järvinen wrote:
> > The SoC also has a pin to select between RS485 and RS232. With a combo 
> > transceiver, TCR-based heuristic just runs into the same problems as the 
> > version-based one did.
> 
> I thought this was about detecting whether hardware-assisted DE assertion
> may be used (versus software-controlled), not about whether to enable
> RS-485 mode.  Right?

HW DE assertion only works when RS485 mode is enabled so I don't see how 
these questions could be easily decoupled like that. That's assuming with 
"software-controlled" you mean RTS(RS232)+em485?


-- 
 i.