From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Neukum Subject: Re: Moxa UPort 1150 and =?UTF-8?Q?RS-422=2F485=E2=80=A6?= what's the "proper" way to switch modes Date: Tue, 27 Jun 2017 14:08:51 +0200 Message-ID: <1498565331.30390.5.camel@suse.com> References: <4a469222-d48d-f498-f2db-ca582295adc3@longlandclan.id.au> <20170627090449.GG3025@localhost> <42601356-656d-57d0-d366-a0933780b8f9@longlandclan.id.au> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <42601356-656d-57d0-d366-a0933780b8f9-3e+Fe6x+DsgJbe36r25VNhCuuivNXqWP@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stuart Longland , Johan Hovold Cc: Alan Cox , linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-serial@vger.kernel.org Am Dienstag, den 27.06.2017, 19:43 +1000 schrieb Stuart Longland: > Maybe a good start would be a "standard" option (referring to the > physical signalling standard, TTL/RS-232/RS-422/RS-485), that lists the > available standards when read and shows the "selected" standard in > brackets (like the 'trigger' option of the LEDs sysfs interface)… so for > this case: > > # cat /sys/class/tty/ttyUSB0/standard > [rs232] rs422 rs485 rs485fd > > and to select 4-wire ("full duplex") RS-485, one does: > # echo rs485fd > /sys/class/tty/ttyUSB0/standard This looks like something that people will put into udev. So the switch will be done via udev, but the user not necessarily started via udev. Looks like a race to me. And what do you if the interface is already opened and the sysfs interface is used? Regards Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html