From: Marc Pignat <marc.pignat-7TsPiqsLilE@public.gmane.org>
To: Atsushi Nemoto <anemo-7JcRY8pycbNHfZP73Gtkiw@public.gmane.org>
Cc: David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>,
spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] atmel_spi: support zero length transfer
Date: Wed, 20 Feb 2008 18:55:01 +0100 [thread overview]
Message-ID: <200802201855.02605.marc.pignat@hevs.ch> (raw)
In-Reply-To: <20080221.005432.07645461.anemo-7JcRY8pycbNHfZP73Gtkiw@public.gmane.org>
Hi!
On Wednesday 20 February 2008, you wrote:
> A spi transfer with zero length is not invalid. Such transfer can be
> used to achieve delay before first CLK edge after chipselect assertion.
How long will be that delay?
If they are really users of that kind of thing, this should be fixed by adding
a "delay_us_before_xfer" field in the struct spi_transfer.
Have you tested it? I think if you start a transfer with 0 len, the ENDRX bit
will never rise, however, I'm not sure about this.
Regards
Marc
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WARNING: multiple messages have this Message-ID (diff)
From: Marc Pignat <marc.pignat@hevs.ch>
To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>,
David Brownell <david-b@pacbell.net>,
spi-devel-general@lists.sourceforge.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] atmel_spi: support zero length transfer
Date: Wed, 20 Feb 2008 18:55:01 +0100 [thread overview]
Message-ID: <200802201855.02605.marc.pignat@hevs.ch> (raw)
In-Reply-To: <20080221.005432.07645461.anemo@mba.ocn.ne.jp>
Hi!
On Wednesday 20 February 2008, you wrote:
> A spi transfer with zero length is not invalid. Such transfer can be
> used to achieve delay before first CLK edge after chipselect assertion.
How long will be that delay?
If they are really users of that kind of thing, this should be fixed by adding
a "delay_us_before_xfer" field in the struct spi_transfer.
Have you tested it? I think if you start a transfer with 0 len, the ENDRX bit
will never rise, however, I'm not sure about this.
Regards
Marc
next prev parent reply other threads:[~2008-02-20 17:55 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-20 15:54 [PATCH] atmel_spi: support zero length transfer Atsushi Nemoto
2008-02-20 15:54 ` Atsushi Nemoto
[not found] ` <20080221.005432.07645461.anemo-7JcRY8pycbNHfZP73Gtkiw@public.gmane.org>
2008-02-20 17:55 ` Marc Pignat [this message]
2008-02-20 17:55 ` Marc Pignat
[not found] ` <200802201855.02605.marc.pignat-7TsPiqsLilE@public.gmane.org>
2008-02-21 1:52 ` Atsushi Nemoto
2008-02-21 1:52 ` Atsushi Nemoto
[not found] ` <20080221.105233.41199605.nemoto-IGagC74glE2asRnM1LW+pc8NsWr+9BEh@public.gmane.org>
2008-02-21 9:26 ` Marc Pignat
2008-02-21 9:26 ` Marc Pignat
2008-02-21 19:23 ` David Brownell
[not found] ` <20080221192334.EE97A230A58-ZcXrCSuhvln6VZ3dlLfH/g4gEjPzgfUyLrfjE7I9kuVHxeISYlDBzl6hYfS7NtTn@public.gmane.org>
2008-02-22 9:30 ` Marc Pignat
2008-02-22 9:30 ` Marc Pignat
[not found] ` <200802221030.32263.marc.pignat-7TsPiqsLilE@public.gmane.org>
2008-02-22 14:15 ` Atsushi Nemoto
2008-02-22 14:15 ` Atsushi Nemoto
[not found] ` <20080222.231510.56565462.anemo-7JcRY8pycbNHfZP73Gtkiw@public.gmane.org>
2008-02-22 14:28 ` Ned Forrester
2008-02-22 14:28 ` [spi-devel-general] " Ned Forrester
2008-02-22 19:06 ` David Brownell
[not found] ` <20080222190613.0043B229B4D-ZcXrCSuhvln6VZ3dlLfH/g4gEjPzgfUyLrfjE7I9kuVHxeISYlDBzl6hYfS7NtTn@public.gmane.org>
2008-02-22 19:52 ` Ned Forrester
2008-02-22 19:52 ` [spi-devel-general] " Ned Forrester
2008-02-22 18:58 ` David Brownell
2008-02-22 18:58 ` [spi-devel-general] " David Brownell
2008-02-23 2:55 ` David Brownell
2008-02-23 2:55 ` David Brownell
[not found] ` <200802221855.25892.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-02-25 8:15 ` Marc Pignat
2008-02-25 8:15 ` Marc Pignat
2008-02-22 14:07 ` Ned Forrester
2008-02-22 14:07 ` [spi-devel-general] " Ned Forrester
2008-02-22 19:02 ` David Brownell
[not found] ` <20080222190228.2B0CB28E363-ZcXrCSuhvln6VZ3dlLfH/g4gEjPzgfUyLrfjE7I9kuVHxeISYlDBzl6hYfS7NtTn@public.gmane.org>
2008-02-22 19:36 ` Ned Forrester
2008-02-22 19:36 ` [spi-devel-general] " Ned Forrester
[not found] ` <47BF2455.8030904-/d+BM93fTQY@public.gmane.org>
2008-02-23 2:37 ` David Brownell
2008-02-23 2:37 ` [spi-devel-general] " David Brownell
2008-02-25 0:25 ` Atsushi Nemoto
2008-02-25 0:25 ` [spi-devel-general] " Atsushi Nemoto
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