From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753870Ab1I0MNj (ORCPT ); Tue, 27 Sep 2011 08:13:39 -0400 Received: from sestofw01.enea.se ([192.36.1.252]:17722 "HELO mx-3.enea.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1753772Ab1I0MNi (ORCPT ); Tue, 27 Sep 2011 08:13:38 -0400 Message-ID: <4E81BDEE.2080601@enea.com> Date: Tue, 27 Sep 2011 14:13:34 +0200 From: Arvid Brodin User-Agent: Thunderbird 2.0.0.24 (X11/20100411) MIME-Version: 1.0 To: CC: , Hans-Christian Egtvedt , Haavard Skinnemoen , Subject: Re: dma_unmap_single() lacking cache sync on some archs? Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [172.23.1.38] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [Resending with CC to affected parties] Hi, I would expect cache synchronization for DMA_TO_DEVICE and DMA_BIDIRECTIONAL when dma_map_single() is called, and for DMA_FROM_DEVICE and DMA_BIDIRECTIONAL when dma_unmap_single() is called. However, on some architechtures (at least avr32, blackfin, ...), cache synchronization only happens when dma_map_single() is called (and then irrespective of DMA direction). dma_unmap_single() is a no-op for these archs. See e.g. http://lxr.linux.no/#linux+v3.0.4/arch/avr32/include/asm/dma-mapping.h#L117 Isn't this a bug? (Please CC me in responses.) -- Arvid Brodin Enea Services Stockholm AB