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From: Ned Forrester <nforrester@whoi.edu>
To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: marc.pignat@hevs.ch, david-b@pacbell.net,
	spi-devel-general@lists.sourceforge.net,
	linux-kernel@vger.kernel.org
Subject: Re: [spi-devel-general] [PATCH] atmel_spi: support zero length	transfer
Date: Fri, 22 Feb 2008 09:28:11 -0500	[thread overview]
Message-ID: <47BEDBFB.5040305@whoi.edu> (raw)
In-Reply-To: <20080222.231510.56565462.anemo@mba.ocn.ne.jp>

Atsushi Nemoto wrote:

> If the driver could not handle zero length transfer, then the driver
> should reject it (just like unsupported transfer mode).  Then the
> behavior will be 'assert chip select and wait some time' or 'rejected
> by the driver'.

This would be OK.  It would not be hard to fix pxa2xx_spi, for example,
to reject zero-length transfers in DMA mode, as long as it is acceptable
to reject the message in mid-message.  If it were necessary to scan a
whole message for zero-length transfers and refuse to queue an offending
message, then that adds burden to all messages.

-- 
Ned Forrester                                       nforrester@whoi.edu
Oceanographic Systems Lab                                  508-289-2226
Applied Ocean Physics and Engineering Dept.
Woods Hole Oceanographic Institution          Woods Hole, MA 02543, USA
http://www.whoi.edu/sbl/liteSite.do?litesiteid=7212
http://www.whoi.edu/hpb/Site.do?id=1532
http://www.whoi.edu/page.do?pid=10079


  reply	other threads:[~2008-02-22 14:28 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-20 15:54 Atsushi Nemoto
2008-02-20 17:55 ` Marc Pignat
2008-02-21  1:52   ` Atsushi Nemoto
2008-02-21  9:26     ` Marc Pignat
2008-02-21 19:23       ` David Brownell
2008-02-22  9:30         ` Marc Pignat
2008-02-22 14:15           ` Atsushi Nemoto
2008-02-22 14:28             ` Ned Forrester [this message]
2008-02-22 19:06               ` [spi-devel-general] " David Brownell
2008-02-22 19:52                 ` Ned Forrester
2008-02-22 18:58             ` David Brownell
2008-02-23  2:55           ` David Brownell
2008-02-25  8:15             ` Marc Pignat
2008-02-22 14:07         ` [spi-devel-general] " Ned Forrester
2008-02-22 19:02           ` David Brownell
2008-02-22 19:36             ` Ned Forrester
2008-02-23  2:37               ` David Brownell
2008-02-25  0:25               ` Atsushi Nemoto

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