Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934015AbYFTUuc (ORCPT ); Fri, 20 Jun 2008 16:50:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758045AbYFTUuJ (ORCPT ); Fri, 20 Jun 2008 16:50:09 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:51219 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756212AbYFTUuH (ORCPT ); Fri, 20 Jun 2008 16:50:07 -0400 Date: Fri, 20 Jun 2008 13:50:06 -0700 (PDT) Message-Id: <20080620.135006.243389159.davem@davemloft.net> To: stern@rowland.harvard.edu Cc: linux-kernel@vger.kernel.org, antonio.lin@alcormicro.com, david.vrabel@csr.com Subject: Re: Scatter-gather list constraints From: David Miller In-Reply-To: References: X-Mailer: Mew version 5.2 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 961 Lines: 21 From: Alan Stern Date: Fri, 20 Jun 2008 16:30:25 -0400 (EDT) > This question arises in connection with wireless USB mass-storage > devices. The controller driver requires that all DMA segments > in a transfer, other than the last one, have a multiple of 1024 bytes. > But we're sometimes getting s-g lists where an element contains an odd > number of 512-byte sectors, and of course it doesn't work. The generic device layer DMA bits does have ways to indicate DMA restrictions such as maximum segment size, but not something like this. This is a pretty strange requirement, and would be probably be quite difficult to support across the board just to handle this strange device :) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/