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From: Rogier Wolff <R.E.Wolff@BitWizard.nl>
To: Stuart MacDonald <stuartm@connecttech.com>,
	"'Rogier Wolff'" <R.E.Wolff@BitWizard.nl>,
	"'Alan Cox'" <alan@lxorguk.ukuu.org.uk>,
	"'linux-os \(Dick Johnson\)'" <linux-os@analogic.com>,
	"'Krzysztof Halasa'" <khc@pm.waw.pl>,
	"'David Woodhouse'" <dwmw2@infradead.org>,
	linux-serial@vger.kernel.org,
	"'LKML'" <linux-kernel@vger.kernel.org>
Subject: Re: Serial custom speed deprecated?
Date: Tue, 29 Aug 2006 08:20:49 +0200	[thread overview]
Message-ID: <20060829062049.GA18752@bitwizard.nl> (raw)
In-Reply-To: <20060828200918.GA959@flint.arm.linux.org.uk>

On Mon, Aug 28, 2006 at 09:09:18PM +0100, Russell King wrote:

> So, while I whole heartedly agree with passing baud rates
> numerically, I do not think we need any of this inexact flagging
> nonsense provided we implement something as userland programs expect
> - iow, the POSIX behaviour.

I fully agree we should implement Posix behaviour. Wether that specifies
what userland programmers expect is where I disagree. 

If you happen to change RTS/CTS at the same time as you change baud,
the call will return succes, even though the most important part (for
you) of your call failed. Note that if the succes of the call depends
on the previous state of RTS/CTS. Thus the error will depend on
whatever happened before. This creates difficult-to-diagnose problems
for sysadmins. 

Anyway, this would not happen if the programmer had read the full text
of the POSIX spec. IMHO, most programmers have a good idea of the
filosopy, and program against that: If some call fails it returns
error.

Anyway, here I am again rambling against the Posix spec. But again:
we should implement POSIX as good as we can. Alan already did the
most important footwork. Good job!

	Roger. 

-- 
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2600998 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
Q: It doesn't work. A: Look buddy, doesn't work is an ambiguous statement. 
Does it sit on the couch all day? Is it unemployed? Please be specific! 
Define 'it' and what it isn't doing. --------- Adapted from lxrbot FAQ

WARNING: multiple messages have this Message-ID (diff)
From: Rogier Wolff <R.E.Wolff@BitWizard.nl>
To: Stuart MacDonald <stuartm@connecttech.com>,
	'Rogier Wolff' <R.E.Wolff@BitWizard.nl>,
	'Alan Cox' <alan@lxorguk.ukuu.org.uk>,
	"'linux-os (Dick Johnson)'" <linux-os@analogic.com>,
	'Krzysztof Halasa' <khc@pm.waw.pl>,
	'David Woodhouse' <dwmw2@infradead.org>,
	linux-serial@vger.kernel.org,
	'LKML' <linux-kernel@vger.kernel.org>
Subject: Re: Serial custom speed deprecated?
Date: Tue, 29 Aug 2006 08:20:49 +0200	[thread overview]
Message-ID: <20060829062049.GA18752@bitwizard.nl> (raw)
In-Reply-To: <20060828200918.GA959@flint.arm.linux.org.uk>

On Mon, Aug 28, 2006 at 09:09:18PM +0100, Russell King wrote:

> So, while I whole heartedly agree with passing baud rates
> numerically, I do not think we need any of this inexact flagging
> nonsense provided we implement something as userland programs expect
> - iow, the POSIX behaviour.

I fully agree we should implement Posix behaviour. Wether that specifies
what userland programmers expect is where I disagree. 

If you happen to change RTS/CTS at the same time as you change baud,
the call will return succes, even though the most important part (for
you) of your call failed. Note that if the succes of the call depends
on the previous state of RTS/CTS. Thus the error will depend on
whatever happened before. This creates difficult-to-diagnose problems
for sysadmins. 

Anyway, this would not happen if the programmer had read the full text
of the POSIX spec. IMHO, most programmers have a good idea of the
filosopy, and program against that: If some call fails it returns
error.

Anyway, here I am again rambling against the Posix spec. But again:
we should implement POSIX as good as we can. Alan already did the
most important footwork. Good job!

	Roger. 

-- 
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2600998 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
Q: It doesn't work. A: Look buddy, doesn't work is an ambiguous statement. 
Does it sit on the couch all day? Is it unemployed? Please be specific! 
Define 'it' and what it isn't doing. --------- Adapted from lxrbot FAQ

  reply	other threads:[~2006-08-29  6:20 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-08-23 21:41 Serial custom speed deprecated? Stuart MacDonald
2006-08-24  9:18 ` David Woodhouse
2006-08-24 12:41   ` Stuart MacDonald
2006-08-24 13:19     ` Alan Cox
2006-08-24 13:03       ` David Woodhouse
2006-08-24 16:27   ` Krzysztof Halasa
2006-08-24 17:41     ` Alan Cox
2006-08-24 18:51       ` Krzysztof Halasa
2006-08-24 20:43         ` linux-os (Dick Johnson)
2006-08-24 20:43           ` linux-os (Dick Johnson)
2006-08-24 22:11           ` Alan Cox
2006-08-27  6:52             ` Rogier Wolff
2006-08-27  6:52               ` Rogier Wolff
2006-08-27 10:00               ` Russell King
2006-08-28 14:14               ` Stuart MacDonald
2006-08-28 14:14                 ` Stuart MacDonald
2006-08-28 20:09                 ` Russell King
2006-08-29  6:20                   ` Rogier Wolff [this message]
2006-08-29  6:20                     ` Rogier Wolff
2006-08-29  7:46                     ` Russell King
2006-08-25 15:17           ` Stuart MacDonald
2006-08-25 15:17             ` Stuart MacDonald
2006-08-25 15:52             ` linux-os (Dick Johnson)
2006-08-25 15:52               ` linux-os (Dick Johnson)
2006-08-24 22:43         ` Alan Cox
2006-08-25 10:58           ` Krzysztof Halasa
2006-08-25 15:21           ` Stuart MacDonald
2006-08-25 15:21             ` Stuart MacDonald
2006-08-25 19:32             ` Russell King
2006-08-25 20:21               ` Stuart MacDonald
2006-08-25 20:21                 ` Stuart MacDonald
2006-08-25 20:54                 ` linux-os (Dick Johnson)
2006-08-25 20:54                   ` linux-os (Dick Johnson)
2006-08-25 20:39               ` Theodore Tso
2006-08-26 12:16                 ` Krzysztof Halasa
2006-08-25 15:10         ` Stuart MacDonald
2006-08-25 15:10           ` Stuart MacDonald
2006-08-24 22:05       ` Russell King
2006-08-25 15:01       ` Stuart MacDonald
2006-08-25 15:01         ` Stuart MacDonald
     [not found] <6N8LR-22A-5@gated-at.bofh.it>
     [not found] ` <6Njxz-797-13@gated-at.bofh.it>
     [not found]   ` <6NqfR-5Ld-49@gated-at.bofh.it>
     [not found]     ` <6NrbQ-7Ab-27@gated-at.bofh.it>
     [not found]       ` <6NsB4-2GL-37@gated-at.bofh.it>
     [not found]         ` <6NvSc-1go-31@gated-at.bofh.it>
2006-08-25 11:40           ` Nick Craig-Wood
2006-08-26 18:16 linux
2006-08-26 19:37 ` Ian Stirling
2006-08-26 20:30   ` linux
2006-08-28 12:17 ` linux-os (Dick Johnson)
2006-08-28 14:39   ` Alan Cox
2006-08-28 14:50     ` linux-os (Dick Johnson)
2006-08-28 15:51       ` Michael Poole
2006-08-28 16:57         ` linux-os (Dick Johnson)
2006-08-28 17:40           ` Michael Poole
2006-08-28 18:04             ` linux-os (Dick Johnson)
2006-08-28 17:01       ` Alan Cox
2006-08-28 17:24         ` linux
2006-08-26 19:35 linux

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