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From: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
To: Rob Herring <robh@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	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>,
	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: Tue, 17 Jan 2017 14:57:29 +0000	[thread overview]
Message-ID: <20170117145729.6c3a9413@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <20170116225436.17505-3-robh@kernel.org>

On Mon, 16 Jan 2017 16:54:29 -0600
Rob Herring <robh@kernel.org> 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.

Signed-off-by: Alan Cox <alan@linux.intel.com>

Alan

  reply	other threads:[~2017-01-17 14:58 UTC|newest]

Thread overview: 42+ 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 [this message]
2017-01-19 13:37   ` Greg Kroah-Hartman
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
2017-01-18 21:26       ` Rob Herring
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  1:36   ` msuchanek
2017-01-20  9:50   ` Sebastian Reichel
2017-01-20  9:50     ` Sebastian Reichel
2017-01-20 13:44 ` Greg Kroah-Hartman
2017-01-20 13:44   ` Greg Kroah-Hartman
2017-01-20 13:55 ` Linus Walleij
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 14:23       ` H. Nikolaus Schaller
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 15:26       ` Linus Walleij
2017-01-20 16:16       ` Andy Shevchenko
2017-01-20 16:16         ` Andy Shevchenko
2017-01-27 20:02         ` Pavel Machek
2017-01-27 20:02           ` Pavel Machek
2017-01-20 20:23       ` Pavel Machek

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