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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Mychaela Falconia <mychaela.falconia@gmail.com>
Cc: Johan Hovold <johan@kernel.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	"Mychaela N . Falconia" <falcon@freecalypso.org>,
	linux-serial@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/7] tty: add flag to suppress ready signalling on open
Date: Thu, 10 Dec 2020 10:06:11 +0100	[thread overview]
Message-ID: <X9HlA17uI7I3Cuxw@kroah.com> (raw)
In-Reply-To: <CA+uuBqYTzXCHGY8QnP+OQ5nRNAbqx2rMNzLM7OKLM1_4AzzinQ@mail.gmail.com>

On Wed, Dec 09, 2020 at 02:49:45PM -0800, Mychaela Falconia wrote:
> Greg K-H wrote:
> 
> > I think we need more review for the rest of the series.  This does
> > change the way serial ports work in a non-traditional way (i.e. using
> > sysfs instead of terminal settings).
> 
> But the problem is that the current status quo is fundamentally broken
> for those hardware devices in which DTR and/or RTS have been repurposed
> for something other than modem and flow control.  Right now whenever a
> "cold" (never previously opened) serial port is opened for the first
> time, that open action immediately and unstoppably asserts both DTR
> and RTS hardware outputs, without giving userspace any opportunity to
> say "no, please don't do it".  Yes, this behaviour is codified in a
> bunch of standards that ultimately trace back to 1970s Original UNIX,
> but just because it is a standard does not make it right - this
> Unix/POSIX/Linux "standard" serial port behaviour is a bug, not a
> feature.

Thanks for the long response, but I think you have to realize that
creating a new api for something that has been "how things work" since
the 1970's should not be taken lightly.  No matter if it was a bug or
not, changing user-visable behavior is not a trivial thing.  What we
come up with here has to stand the test of time of being able to be
supported properly for the next 40+ years.

thanks,

greg k-h

  reply	other threads:[~2020-12-10  9:22 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-02 11:39 [PATCH v2 0/7] tty: add flag to suppress ready signalling on open Johan Hovold
2020-12-02 11:39 ` [PATCH v2 1/7] tty: use assign_bit() in port-flag accessors Johan Hovold
2020-12-02 11:39 ` [PATCH v2 2/7] tty: use const parameters " Johan Hovold
2020-12-02 11:39 ` [PATCH v2 3/7] tty: add port flag to suppress ready signalling on open Johan Hovold
2020-12-02 11:39 ` [PATCH v2 4/7] serial: core: add sysfs attribute " Johan Hovold
2020-12-02 11:39 ` [PATCH v2 5/7] USB: serial: " Johan Hovold
2020-12-02 11:39 ` [PATCH v2 6/7] USB: serial: ftdi_sio: pass port to quirk port_probe functions Johan Hovold
2020-12-02 11:39 ` [PATCH v2 7/7] USB: serial: ftdi_sio: add support for FreeCalypso DUART28C adapter Johan Hovold
2020-12-02 18:07 ` [PATCH v2 0/7] tty: add flag to suppress ready signalling on open Mychaela Falconia
2020-12-03  9:21   ` Johan Hovold
2020-12-09 14:30 ` Greg Kroah-Hartman
2020-12-09 15:10   ` Johan Hovold
2020-12-09 22:49   ` Mychaela Falconia
2020-12-10  9:06     ` Greg Kroah-Hartman [this message]
2020-12-10 10:41     ` Maarten Brock
2020-12-10 10:50       ` Greg Kroah-Hartman
2020-12-10 12:05         ` Maarten Brock
2020-12-10 13:01           ` Greg Kroah-Hartman
2020-12-10 18:59             ` Mychaela Falconia
2020-12-11  8:46               ` Jiri Slaby
2020-12-11 16:08                 ` Greg Kroah-Hartman
2020-12-11 15:51               ` Maarten Brock
2020-12-11 16:08               ` Greg Kroah-Hartman
2020-12-14 14:21               ` Johan Hovold
2020-12-18 18:03                 ` Mychaela Falconia
2021-01-07 15:25                   ` Greg Kroah-Hartman
     [not found]                   ` <YBPxG+i/ZLP8/wg1@hovoldconsulting.com>
2021-01-31  0:18                     ` Mychaela Falconia
2021-01-31  5:24                       ` Greg Kroah-Hartman
2020-12-11 10:46             ` Johan Hovold
2020-12-11 10:41       ` Johan Hovold

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