Linux Serial subsystem development
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From: Alan Cox <gnomes-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
To: Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Oliver Neukum <oneukum-IBi9RG/b67k@public.gmane.org>,
	Stuart Longland
	<stuartl-3e+Fe6x+DsgJbe36r25VNhCuuivNXqWP@public.gmane.org>,
	linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: Moxa UPort 1150 and RS-422/485… what's the "proper" way to switch modes
Date: Thu, 29 Jun 2017 20:50:32 +0100	[thread overview]
Message-ID: <20170629205032.743ab235@alans-desktop> (raw)
In-Reply-To: <20170628153439.GC17630@localhost>

So IMHO there are two cases

1. The configuration is fixed in the hardware - in which case we should
automatically set it in kernel, or from device tree.

2. The configuration is soft - in which case you need an ioctl you can
use on the port to change it - irrespective of whether sysfs also handles
it. For simple permissions reasons and also to avoid races you need that
ioctl.

We intentionally have lots of spare space left to extend the RS485 ioctl,
and we have termiox which contains even more room and historically in
other Unixen dealt with all sorts of weird and wonderful parameters used
on stuff like synchronous ports.

Alan
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  reply	other threads:[~2017-06-29 19:50 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <4a469222-d48d-f498-f2db-ca582295adc3@longlandclan.id.au>
     [not found] ` <4a469222-d48d-f498-f2db-ca582295adc3-3e+Fe6x+DsgJbe36r25VNhCuuivNXqWP@public.gmane.org>
2017-06-27  9:04   ` Moxa UPort 1150 and RS-422/485… what's the "proper" way to switch modes Johan Hovold
2017-06-27  9:43     ` Stuart Longland
     [not found]       ` <42601356-656d-57d0-d366-a0933780b8f9-3e+Fe6x+DsgJbe36r25VNhCuuivNXqWP@public.gmane.org>
2017-06-27 12:08         ` Oliver Neukum
     [not found]           ` <1498565331.30390.5.camel-IBi9RG/b67k@public.gmane.org>
2017-06-27 22:07             ` Stuart Longland
     [not found]               ` <ae2907c2-cb0f-61e4-c6f2-af3dcec93ace-3e+Fe6x+DsgJbe36r25VNhCuuivNXqWP@public.gmane.org>
2017-06-28  9:19                 ` Oliver Neukum
     [not found]                   ` <1498641549.10278.5.camel-IBi9RG/b67k@public.gmane.org>
2017-06-28 12:01                     ` Greg KH
     [not found]                       ` <20170628120120.GA10502-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-06-28 12:41                         ` Oliver Neukum
     [not found]                           ` <1498653709.10278.17.camel-IBi9RG/b67k@public.gmane.org>
2017-06-28 14:59                             ` Bjørn Mork
2017-06-28 15:35                 ` Johan Hovold
2017-06-28 15:34             ` Johan Hovold
2017-06-29 19:50               ` Alan Cox [this message]
2017-07-03  8:51                 ` Johan Hovold
2017-06-28 15:16         ` Johan Hovold
2017-08-18  2:56   ` [PATCH] USB: serial: ti_usb_3410_5052: Port uart_mode from io_ti Stuart Longland
     [not found]     ` <20170818025659.4402-1-stuartl-EoQOJlg3kTYQrrorzV6ljw@public.gmane.org>
2017-08-18  3:16       ` Stuart Longland
2017-08-19 20:40       ` Maksim Salau
     [not found]         ` <20170819234056.37c7d339-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-08-19 20:47           ` Stuart Longland
2017-08-28  8:56       ` Greg KH

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