linux-kernel - Re: [PATCH 5/8] serial: 8250: reject delaying RTS with RS485

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Message-ID: <20111117101426.GD2535@pengutronix.de>
Date:	Thu, 17 Nov 2011 11:14:26 +0100
From:	Wolfram Sang <w.sang@...gutronix.de>
To:	Claudio Scordino <claudio@...dence.eu.com>
Cc:	linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
	Alan Cox <alan@...ux.intel.com>,
	Juergen Beisert <jbe@...gutronix.de>,
	Matthias Fuchs <mfuchs@...fu.de>
Subject: Re: [PATCH 5/8] serial: 8250: reject delaying RTS with RS485


> The delay must not necessarily be done by hardware. The drivers/tty/serial/crisv10.c 
> driver, for example, delays through a msleep.
> 
> I don't know if having a software delay in this driver can make sense in some particular 
> circumstance.

Uuuh, I would be against software delays for the same reason why we
don't accept software based direction switching: No guarantees. msleep()
might easily delay longer than what was requested. Or are delay_rts
values to be interpreted as "delay at least"?

Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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