From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Paterniani Subject: Re: SPI controller bugfixes needed (full duplex + DMA, data corruption) Date: Tue, 18 Nov 2008 09:30:02 +0100 Message-ID: <49227D0A.40506@swapp-eng.it> References: <200811151422.32748.david-b@pacbell.net> <20081118075215.GD9553@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: David Brownell , spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org To: Sascha Hauer Return-path: In-Reply-To: <20081118075215.GD9553-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org I have an iMX1 based HW running kernel 2.6.25.8. I checked the patch and to seems to be ok (solves old problems on full duplex transfers). Regards, -- Andrea Sascha Hauer ha scritto: > Hi David, > > On Sat, Nov 15, 2008 at 02:22:32PM -0800, David Brownell wrote: > >> Hi, >> >> We recently turned up a bug in the pxa2xx SPI driver, which >> turns out to also be present in the spi_imx.c and au1550_spi.c >> drivers too. >> >> Briefly, full duplex transfers are allowed to share the >> same buffer (or partially overlap it), which means that >> the dma mapping operations must be done in a safe order: >> >> - first map the TX buffer, so cache data gets written >> to memory where the DMA will pick it up; >> >> - then map the RX buffer, so that cache entries (with >> soon-to-be-stale data) get removed. >> >> Doing it the other order, as is done with spi_imx and >> with au1550_spi, causes data corruption by discarding >> data from the cache *before* writing it to memory. >> >> If you can do it, it'd be good to see this fixed before >> the 2.6.28 kernel ships. >> > > Hm, this is a non trivial fix. I don't have a MX1 based hardware with > something on the SPI bus handy, so this would be a shot in the dark for > me. I hope Andrea jumps in, otherwise we'll have to wait till the driver > works on MX2. > > Sascha > > -- ------------------------------------------------------------------------ *Ing. Andrea Paterniani* *SWAPP* - Studio Professionale Via degli Abeti, 312 - 61100 Pesaro Tel 0721 24256 Fax 178 220 8730 a.paterniani-03BXCEkGbFHYGGNLXY5/rw@public.gmane.org www.swapp-eng.it ------------------------------------------------------------------------ ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/