From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ned Forrester Subject: Re: SPI TX andRX buffer overlap Date: Fri, 14 Nov 2008 18:10:50 -0500 Message-ID: <491E057A.9040507@whoi.edu> References: <491C87BF.6030905@whoi.edu> <200811141430.53146.david-b@pacbell.net> <491E033E.9010008@whoi.edu> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: spi-devel To: David Brownell Return-path: In-Reply-To: <491E033E.9010008-/d+BM93fTQY@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 Ned Forrester wrote: > Is calling dma_map_single() twice on the same block of memory supposed > to be OK? "Linux Device Drivers" does not discuss this, but it seems > unlikely that it is acceptable. Maybe you have to unmap in the reverse > order of mapping; I will test that. Nope, it fails either way. It does not look like double mapping is a good idea. -- Ned Forrester nforrester-/d+BM93fTQY@public.gmane.org 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 ------------------------------------------------------------------------- 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=/