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Date:   Thu, 17 Feb 2022 16:36:57 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Grant Edwards <grant.b.edwards@gmail.com>
Cc:     linux-serial@vger.kernel.org
Subject: Re: Opening already open serial port now sets RTS and DTR?
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On Thu, Feb 17, 2022 at 03:28:00PM -0000, Grant Edwards wrote:
> It used to be that opening a serial port only set RTS and DTR if it
> was a "first open". If the port was already open, subsequent opens
> didn't mess up RTS and DTR. This was a very useful behavior in the
> embedded world where RTS and DTR are often used to power and or
> control things (reset lines, mode controls, line driver enables,
> etc.).
> 
> This seems to have changed, and now _every_ open sets RTS and DTR even
> if the port was already open and RTS and DTR had already been put in
> the desired state.

When did it change?  Any chance you can do 'git bisect' to track it
down?

And what hardware are you using here?  Different hardware works
differently in this way at times.

thanks,

greg k-h