From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755652AbYI1PyN (ORCPT ); Sun, 28 Sep 2008 11:54:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753425AbYI1PsE (ORCPT ); Sun, 28 Sep 2008 11:48:04 -0400 Received: from yx-out-2324.google.com ([74.125.44.30]:10458 "EHLO yx-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754220AbYI1PsA (ORCPT ); Sun, 28 Sep 2008 11:48:00 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:mime-version:content-type :content-transfer-encoding:content-disposition; b=SkxPqIgqkLY3SdceAy2WckeMfWi7KXJpkR+lbPRSQrn5XBVRKXnvJwhOqSULKxJLx+ 3jjGxedeyVx6/k+9ax53RK5jn0r74IG4NX7LYLKefRhXcWS2HGVP3/yReC5AzX5iOY+I i+qdK5PLI2Ot80cVLztDntJhTecm9uG/dzqA8= Message-ID: Date: Sun, 28 Sep 2008 17:47:59 +0200 From: "Leon Woestenberg" To: "linux-kernel@vger.kernel.org" Subject: scatterlist.c or dma_map_sg() should coalesce? MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, in 2.6.27+, if I want to create a scatterlist of a large buffer in virtual memory in a device driver, can I expect the scatterlist and/or mapping API to provide me with a minimal list, each entry describing a maximum bus-contiguous piece of memory? (i.e. can I assume coalescing is done for me?). In 2.6.24, dma_map_sg() *may* coalesce, but doesn't do so for my platform, so for optimal DMA transfers the device driver needs to coalesce the list entries. Regards, -- Leon