From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Johan Hovold <johan@kernel.org>
Cc: kernel@pengutronix.de, linux-serial@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, Dan Murphy <dmurphy@ti.com>,
Pavel Machek <pavel@ucw.cz>, Jiri Slaby <jslaby@suse.com>,
linux-leds@vger.kernel.org,
Jacek Anaszewski <jacek.anaszewski@gmail.com>
Subject: Re: [PATCH v6 2/4] tty: rename tty_kopen() and add new function tty_kopen_shared()
Date: Tue, 25 Feb 2020 10:05:51 +0100 [thread overview]
Message-ID: <20200225090551.jhj7sc75neyphbss@pengutronix.de> (raw)
In-Reply-To: <20200225085503.GP32540@localhost>
On Tue, Feb 25, 2020 at 09:55:03AM +0100, Johan Hovold wrote:
> On Thu, Feb 20, 2020 at 12:04:27PM +0100, Uwe Kleine-König wrote:
> > Ah I think I see. tty_driver_lookup_tty() might return NULL which for
> > the trigger driver indicates that tty_kopen_shared should be retried,
> > right?
>
> I'm not sure how best to handle this, but yes, your trigger can only be
> enabled while the port is open currently. And no error is returned to a
> user trying to enable the trigger before it has been opened.
>
> But regardless of the error reporting, I don't think failing when the
> port isn't open is the right thing to do as as this makes the interface
> rather useless since you cannot enable a trigger from for example a udev
> rule.
>
> If this approach is to be used at all, it seems you may need to allocate
> the struct tty when the trigger is enabled. And make sure you don't mess
> up some other assumption in tty core...
My idea is instead to retry opening the device later. At least this
sounds easier.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
next prev parent reply other threads:[~2020-02-25 9:06 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-13 9:15 [PATCH v6 0/4] leds: trigger: implement a tty trigger Uwe Kleine-König
2020-02-13 9:15 ` [PATCH v6 1/4] lib: new helper kstrtodev_t() Uwe Kleine-König
2020-02-19 19:50 ` Andy Shevchenko
2020-02-20 7:49 ` Uwe Kleine-König
2020-02-20 10:22 ` Andy Shevchenko
2020-02-20 10:57 ` Uwe Kleine-König
2020-02-20 11:46 ` Andy Shevchenko
2020-02-20 11:57 ` Andy Shevchenko
2020-02-20 14:01 ` Uwe Kleine-König
2020-02-21 8:42 ` Andy Shevchenko
2020-02-21 10:53 ` Uwe Kleine-König
2020-04-25 7:07 ` Pavel Machek
2020-02-13 9:15 ` [PATCH v6 2/4] tty: rename tty_kopen() and add new function tty_kopen_shared() Uwe Kleine-König
2020-02-19 13:21 ` Johan Hovold
2020-02-19 16:37 ` Uwe Kleine-König
2020-02-19 17:17 ` Johan Hovold
2020-02-20 11:04 ` Uwe Kleine-König
2020-02-25 8:55 ` Johan Hovold
2020-02-25 9:05 ` Uwe Kleine-König [this message]
2020-02-13 9:15 ` [PATCH v6 3/4] tty: new helper function tty_get_icount() Uwe Kleine-König
2020-02-13 9:16 ` [PATCH v6 4/4] leds: trigger: implement a tty trigger Uwe Kleine-König
2020-02-19 10:52 ` Johan Hovold
2020-02-19 11:03 ` Uwe Kleine-König
2020-02-19 11:19 ` Johan Hovold
2020-02-19 12:48 ` Johan Hovold
2020-02-19 10:40 ` [PATCH v6 0/4] " Greg Kroah-Hartman
2020-02-26 14:02 ` Pavel Machek
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