Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220618195031.10975-1-max@enpas.org> <20220627150557.qluqtejrddj5nfif@pengutronix.de>
 <20220627190126.4eb57a2b.max@enpas.org> <CAMuHMdUYCiRC+9UnQB6-2XGp+wOjYq1U_J3bDQT+WNm==mS4qg@mail.gmail.com>
 <20220705094927.vgtxcjh4klw6dcg3@pengutronix.de> <20220705115613.69d32b22.max@enpas.org>
In-Reply-To: <20220705115613.69d32b22.max@enpas.org>
From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Tue, 5 Jul 2022 12:16:08 +0200
Message-ID: <CAMuHMdW5tTVP6cQ6a8KtgYAxb_g1Y52a9+hHwEtNLV3xYpWsVA@mail.gmail.com>
Subject: Re: [PATCH v9] can, tty: can327 CAN/ldisc driver for ELM327 based
 OBD-II adapters
To:     Marc Kleine-Budde <mkl@pengutronix.de>, Max Staudt <max@enpas.org>
Cc:     Wolfgang Grandegger <wg@grandegger.com>, linux-can@vger.kernel.org,
        Vincent Mailhol <vincent.mailhol@gmail.com>,
        Oliver Neukum <oneukum@suse.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Oliver Hartkopp <socketcan@hartkopp.net>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi Marc, Max,

On Tue, Jul 5, 2022 at 11:56 AM Max Staudt <max@enpas.org> wrote:
> On Tue, 5 Jul 2022 11:49:27 +0200
> Marc Kleine-Budde <mkl@pengutronix.de> wrote:
> > On 05.07.2022 11:43:52, Geert Uytterhoeven wrote:
> > > So development started before commit cd6484e1830be260 ("serdev:
> > > Introduce new bus for serial attached devices").  I guess that is
> > > the reason why this driver uses a line discipline, instead of the
> > > serial bus?
> > >
> > > I had a quick glance through the various revisions posted, and it
> > > doesn't seem like anyone mentioned the serial bus.  Would there be
> > > any advantage in migrating to the serial bus?
> >
> > Does serial bus work with hot plug devices like USB Serial Adapters
> > and/or devices that are not described in the device tree?

Probably it cannot work with hot-plug devices yet.
And devices must be described in some way (DT, ACPI), it does not
support auto-detect.

> This is indeed the reason. The device cannot be autodetected, as the
> UART has no identifying information (USB VID/PID or the like, and don't
> forget the BT variants) attached to it, hence the manual attachment.

So you do need a description ;-)

So far I've seen serial bus used with e.g. bluetooth and DT.
I'm wondering if/how people use it with bluetooth connected to a
hot-pluggable device like usb-serial.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds