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Date:   Wed, 3 Nov 2021 09:23:54 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Jochen Mades <jochen@mades.net>
Cc:     linux-serial@vger.kernel.org
Subject: Re: Extending serial port linux driver to toggle RS485 direction pin
 (GPIO)
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A: http://en.wikipedia.org/wiki/Top_post
Q: Were do I find info about this thing called top-posting?
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

A: No.
Q: Should I include quotations after my reply?

http://daringfireball.net/2007/07/on_top

On Wed, Nov 03, 2021 at 08:23:38AM +0100, Jochen Mades wrote:
> Hi Greg,
> 
> thanks for your fast reply. I checked the sources you mentioned below, that helps a bit..
> 
> Could you please give me some more background what you mean with your question:
> > You could do much the same in the pl011_rs485_tx_start() function when
> > SER_RS485_RX_DURING_TX and SER_RS485_RTS_ON_SEND are checked, right?
> 
> Is there already a concept for RS485 drivers?

Yes, RS485 drivers control lines like you are looking for in order to
properly handle the protocol requirements.

> ...or where to find "pl011_rs485_tx_start()"?

Look in the kernel source tree for that function, that's in the driver
you were looking to modify, right?

thanks,

greg k-h