From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Rob Herring <robh@kernel.org>
Cc: Marcel Holtmann <marcel@holtmann.org>,
Jiri Slaby <jslaby@suse.com>, Sebastian Reichel <sre@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
"Dr . H . Nikolaus Schaller" <hns@goldelico.com>,
Peter Hurley <peter@hurleysoftware.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
Loic Poulain <loic.poulain@intel.com>,
Pavel Machek <pavel@ucw.cz>, NeilBrown <neil@brown.name>,
Linus Walleij <linus.walleij@linaro.org>,
linux-bluetooth@vger.kernel.org, linux-serial@vger.kernel.org,
linux-kernel@vger.kernel.org, Alan Cox <alan@linux.intel.com>
Subject: Re: [PATCH v2 2/9] tty_port: allow a port to be opened with a tty that has no file handle
Date: Thu, 19 Jan 2017 14:37:18 +0100 [thread overview]
Message-ID: <20170119133718.GA6072@kroah.com> (raw)
In-Reply-To: <20170116225436.17505-3-robh@kernel.org>
On Mon, Jan 16, 2017 at 04:54:29PM -0600, Rob Herring wrote:
> From: Alan Cox <alan@linux.intel.com>
>
> Let us create tty objects entirely in kernel space. Untested proposal to
> show why all the ideas around rewriting half the uart stack are not needed.
>
> With this a kernel created non file backed tty object could be used to handle
> data, and set terminal modes. Not all ldiscs can cope with this as N_TTY in
> particular has to work back to the fs/tty layer.
>
> The tty_port code is however otherwise clean of file handles as far as I can
> tell as is the low level tty port write path used by the ldisc, the
> configuration low level interfaces and most of the ldiscs.
>
> Currently you don't have any exposure to see tty hangups because those are
> built around the file layer. However a) it's a fixed port so you probably
> don't care about that b) if you do we can add a callback and c) you almost
> certainly don't want the userspace tear down/rebuild behaviour anyway.
>
> This should however be sufficient if we wanted for example to enumerate all
> the bluetooth bound fixed ports via ACPI and make them directly available.
> It doesn't deal with the case of a user opening a port that's also kernel
> opened and that would need some locking out (so it returned EBUSY if bound
> to a kernel device of some kind). That needs resolving along with how you
> "up" or "down" your new bluetooth device, or enumerate it while providing
> the existing tty API to avoid regressions (and to debug).
>
> Alan
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-By: Sebastian Reichel <sre@kernel.org>
> ---
> Alan, Need your SoB here.
Rob, as this patch is flowing through you, I need your signed-off-by as
well if I am to take it.
thanks,
greg k-h
next prev parent reply other threads:[~2017-01-19 13:37 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-16 22:54 [PATCH v2 0/9] Serial slave device bus Rob Herring
2017-01-16 22:54 ` [PATCH v2 1/9] tty: move the non-file related parts of tty_release to new tty_release_struct Rob Herring
2017-01-16 22:54 ` [PATCH v2 2/9] tty_port: allow a port to be opened with a tty that has no file handle Rob Herring
2017-01-17 14:57 ` One Thousand Gnomes
2017-01-19 13:37 ` Greg Kroah-Hartman [this message]
2017-01-19 15:05 ` Rob Herring
2017-01-19 15:23 ` Rob Herring
2017-01-16 22:54 ` [PATCH v2 3/9] tty_port: make tty_port_register_device wrap tty_port_register_device_attr Rob Herring
2017-01-16 22:54 ` [PATCH v2 4/9] tty: constify tty_ldisc_receive_buf buffer pointer Rob Herring
2017-01-19 16:24 ` Greg Kroah-Hartman
2017-01-16 22:54 ` [PATCH v2 5/9] tty_port: Add port client functions Rob Herring
2017-01-16 22:54 ` [PATCH v2 6/9] dt/bindings: Add a serial/UART attached device binding Rob Herring
2017-01-16 22:54 ` [PATCH v2 7/9] serdev: Introduce new bus for serial attached devices Rob Herring
2017-01-18 11:53 ` Frédéric Danis
2017-01-18 21:26 ` Rob Herring
2017-01-16 22:54 ` [PATCH v2 8/9] serdev: add a tty port controller driver Rob Herring
2017-01-18 12:42 ` Andy Shevchenko
2017-01-18 15:03 ` Rob Herring
2017-01-16 22:54 ` [PATCH v2 9/9] tty_port: register tty ports with serdev bus Rob Herring
2017-01-17 11:07 ` [PATCH v2 0/9] Serial slave device bus Pavel Machek
2017-01-20 1:36 ` msuchanek
2017-01-20 9:50 ` Sebastian Reichel
2017-01-20 13:44 ` Greg Kroah-Hartman
2017-01-20 13:55 ` Linus Walleij
2017-01-20 14:14 ` Marcel Holtmann
2017-01-20 14:23 ` H. Nikolaus Schaller
2017-01-20 14:22 ` GPS drivers (was Re: [PATCH v2 0/9] Serial slave device bus) Pavel Machek
2017-01-20 15:26 ` Linus Walleij
2017-01-20 16:16 ` Andy Shevchenko
2017-01-27 20:02 ` Pavel Machek
2017-01-20 20:23 ` Pavel Machek
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