From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933243Ab0HLAPH (ORCPT ); Wed, 11 Aug 2010 20:15:07 -0400 Received: from www.tglx.de ([62.245.132.106]:47122 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932986Ab0HLAO4 (ORCPT ); Wed, 11 Aug 2010 20:14:56 -0400 Date: Thu, 12 Aug 2010 02:14:54 +0200 From: "Hans J. Koch" To: Leon Woestenberg Cc: "Hans J. Koch" , Tom Lyon , mst@redhat.com, gregkh@suse.de, chrisw@sous-sol.org, joro@8bytes.org, avi@redhat.com, linux-kernel@vger.kernel.org Subject: Re: UIO DMA to userspace question Message-ID: <20100812001453.GC6411@local> References: <20100809111155.GB2569@local> <20100810001244.GD2569@local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 11, 2010 at 08:42:35PM +0200, Leon Woestenberg wrote: [...] > > I am currently refraining from using UIO, as I don't like the head > ache feature :-) Well, if you need feature X, capability Y, or usecase Z, feel free to send patches. I (and several of my colleagues) wrote quite a lot of UIO drivers for various chips in the last 4 years. I never had a device that needed DMA on my desk yet, otherwise support for it would be in mainline now. UIO was mainly invented to prevent people from writing large character device drivers that will never make it to mainline, and then having to maintain them off-tree. It is not a general purpose driver interface but a small framework to handle a special class of hardware that doesn't fit into any other subsystem. If you've got such hardware, and you need a certain feature, think about how it can be done, and let us know. Thanks, Hans > > Regards, > -- > Leon