From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755398Ab2A0OcG (ORCPT ); Fri, 27 Jan 2012 09:32:06 -0500 Received: from smtp-out-222.synserver.de ([212.40.185.222]:1056 "EHLO smtp-out-222.synserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751544Ab2A0OcE (ORCPT ); Fri, 27 Jan 2012 09:32:04 -0500 X-SynServer-TrustedSrc: 1 X-SynServer-AuthUser: lars@metafoo.de X-SynServer-PPID: 14128 Message-ID: <4F22B593.3010402@metafoo.de> Date: Fri, 27 Jan 2012 15:32:51 +0100 From: Lars-Peter Clausen User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.24) Gecko/20111114 Iceowl/1.0b2 Icedove/3.1.16 MIME-Version: 1.0 To: Vinod Koul , Russell King CC: "linux-kernel@vger.kernel.org" Subject: How is dmaengine_prep_slave_single supposed to be used? Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I've tried using dmaengine_prep_slave_single in one of my drivers an run into an issue, the dma_address attribute of the sg element is not initialized and thus the dma transfer and the DMA transfer fails. Quoting from Documentation/dmaengine.txt: The peripheral driver is expected to have mapped the scatterlist for the DMA operation prior to calling device_prep_slave_sg, and must keep the scatterlist mapped until the DMA operation has completed. So this is clearly not the case with dmaengine_prep_slave_single, so I'm wondering how is ut supposed to be used and can it work properly at all? Thanks, - Lars