From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.whoi.edu (zeratul.whoi.edu [128.128.76.62]) by ozlabs.org (Postfix) with ESMTP id 95F95DDDFE for ; Fri, 27 Jul 2007 14:03:40 +1000 (EST) Message-ID: <46A967D5.30606@whoi.edu> Date: Thu, 26 Jul 2007 23:34:45 -0400 From: Ned Forrester MIME-Version: 1.0 To: David Brownell Subject: Re: [spi-devel-general] [PATCH 2/3] [SPI] Add new mode: SPI_LOOP References: <20070726134754.GA3539@localhost.localdomain> <20070726135051.GB5550@localhost.localdomain> <200707262007.07537.david-b@pacbell.net> In-Reply-To: <200707262007.07537.david-b@pacbell.net> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Cc: spi-devel-general@lists.sourceforge.net, Stephen Street , linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , David Brownell wrote: > On Thursday 26 July 2007, Anton Vorontsov wrote: >> Loopback mode is supported by various controllers, this mode >> is useful for testing, especially in conjunction with spidev >> driver. > > ISTR that Stephen Street provided a loopback mode for debug > in his pxa2xx_spi code. And I know you're fight that this > mode shows up in a lot of hardware. > > Comments, anyone? This seems like a fair way to expose this > mechanism. And I tend to agree that it'd mostly be useful in > conjunction with "spidev". Yes, it is in pxa2xx_spi. It is passed in a structure that is attached to spi_board_info.controller_data. I have used it to great effect to test data modes in the driver for which I have no external hardware support: various bits/word, clock frequencies, fifo thresholds, dma burst sizes, etc. It works for me if this is moved to struct spi_device. I don't think I have any code that could be readily turned into a generic test program. -- 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