From: Stephen Street <stephen@streetfiresound.com>
To: David Brownell <david-b@pacbell.net>
Cc: Vitaly Wool <vwool@ru.mvista.com>,
linux-kernel@vger.kernel.org, dpervushin@gmail.com,
akpm@osdl.org, greg@kroah.com, basicmark@yahoo.com,
komal_shah802003@yahoo.com,
spi-devel-general@lists.sourceforge.net, Joachim_Jaeger@digi.com
Subject: Re: [PATCH 2.6-git] SPI core refresh
Date: Wed, 30 Nov 2005 13:59:10 -0800 [thread overview]
Message-ID: <1133387950.4528.16.camel@localhost.localdomain> (raw)
In-Reply-To: <200511301336.38613.david-b@pacbell.net>
On Wed, 2005-11-30 at 13:36 -0800, David Brownell wrote:
> > - it is DMA-safe
>
> Which as I pointed out is incorrect. The core API (async) has always
> been fully DMA-safe. And a **LOT** lower overhead than yours, which
> allocates buffers behind the back of drivers, and encourages lots of
> memcpy rather than just doing DMA directly to/from the buffers that
> are provided by the SPI protocol drivers.
Minimal (or no) core intervention on the DMA code path is a good thing.
I need to fix some broken hardware with software and must to move 96
bytes from one SPI device to another on the same SPI bus every for 4ms.
Needless memcpy's will cause substantial performance problems in my
application. Thinner is definitely better.
-Stephen
next prev parent reply other threads:[~2005-11-30 21:59 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-30 16:50 [PATCH 2.6-git] SPI core refresh Vitaly Wool
2005-11-30 19:17 ` Russell King
2005-11-30 19:54 ` Greg KH
2005-11-30 20:29 ` Mark Underwood
2005-12-01 7:17 ` Vitaly Wool
2005-12-01 18:31 ` David Brownell
2005-12-02 5:48 ` Vitaly Wool
2005-12-02 18:37 ` Mark Underwood
2005-11-30 21:26 ` David Brownell
2005-11-30 21:27 ` David Brownell
2005-12-12 16:57 ` Vitaly Wool
2005-12-13 22:16 ` David Brownell
2005-11-30 21:36 ` David Brownell
2005-11-30 21:59 ` Stephen Street [this message]
2005-12-01 7:31 ` Vitaly Wool
2005-12-01 7:24 ` Vitaly Wool
-- strict thread matches above, loose matches on Subject: below --
2005-12-01 16:11 Vitaly Wool
2005-12-01 16:21 ` Russell King
2005-12-01 16:30 ` Vitaly Wool
2005-12-01 18:04 ` Stephen Street
2005-12-01 18:22 ` Greg KH
2005-12-02 6:06 ` Vitaly Wool
2005-12-02 18:50 ` Mark Underwood
2005-12-02 20:13 ` Greg KH
2005-12-05 18:01 ` Vitaly Wool
2005-12-08 1:59 ` David Brownell
2005-12-08 6:33 ` Vitaly Wool
2005-12-09 22:55 ` David Brownell
2005-12-10 11:15 ` Vitaly Wool
2005-12-11 12:36 ` Vitaly Wool
2005-12-03 11:44 vitalhome
2005-12-03 11:49 vitalhome
2005-12-03 17:10 ` Mark Underwood
2005-12-03 23:50 ` David Brownell
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