From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751267AbWGDD42 (ORCPT ); Mon, 3 Jul 2006 23:56:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751294AbWGDD42 (ORCPT ); Mon, 3 Jul 2006 23:56:28 -0400 Received: from py-out-1112.google.com ([64.233.166.179]:49669 "EHLO py-out-1112.google.com") by vger.kernel.org with ESMTP id S1751292AbWGDD41 (ORCPT ); Mon, 3 Jul 2006 23:56:27 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=cLKmYRsgFd+a1FRwHBN2qT+lnWcq+ocHoRxpXX0bcwKxnR06LOlAzxBmyysA0qTZJDJeQ2qM748l5Etmu/uMrcDMc9R+BG/dP4/++eaoKGGDl9IbOOb9TOPphfx2clgyy6NbLwSr4+ZmuXlBTM0L9BRYiE2csDAQsGUzEC4Wwus= Message-ID: Date: Mon, 3 Jul 2006 23:56:26 -0400 From: "Daniel Bonekeeper" To: "Greg KH" Subject: Re: Driver for Microsoft USB Fingerprint Reader Cc: "Alon Bar-Lev" , kernelnewbies@nl.linux.org, linux-kernel@vger.kernel.org In-Reply-To: <20060703222645.GA22855@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <9e0cf0bf0607030304n62991dafk19f09e41d69e9ab0@mail.gmail.com> <44A95F12.8080208@gmail.com> <20060703214509.GA5629@kroah.com> <20060703222645.GA22855@kroah.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Maybe this is not a default on the market and is something that is coming... but seems that some USB controllers are coming with DMA capabilities: http://www.usb.org/developers/presentations/pres0501/Augustin_DMA_Implem_Final.ppt http://www.semiconductors.philips.com/pip/isp1183.html Daniel On 7/3/06, Greg KH wrote: > On Mon, Jul 03, 2006 at 06:11:03PM -0400, Daniel Bonekeeper wrote: > > >> Reading Greg's comment, now I'm in doubt if this should really be in > > >> kernel mode or at userspace. Since there is no standard (AFAIK) for > > >> those readers, how should it be done ? > > > > > >It all depends on what you want the userspace interface to be. > > > > > > > That's one problem: I don't want to create one more userspace > > interface for that. I suppose that all the hundreds of fingerprint > > readers that ships with a SDK have their own way of doing that.. that > > looks awfull to me, even though I believe that currently there isn't > > any uniform way of working with fingerprint readers... shouldn't we > > have a way to classify devices ? For example, if I want to list all > > the printers connected via USB (supposing that we have more than one), > > I should be able to request that information from somewhere > > (/dev/usb/printers/* ?) I suppose that different fingerprint readers > > works with different resolutions... we should be able to have an > > unified interface that could tell the userspace the capabilities of > > each fingerprint device (the area size of the scanner, resolution, > > etc)... I think that applies for a lot of devices, not just > > fingerprint readers. Probably there is already something like that. > > Yes, we should have one way of identifying them. I've talked with Dan > already about this in the past. Please see his driver for support for a > few devices already. > > > >> For example, I suppose that some (or all) USB devices may have DMA > > >> capabilities... how is this done ? > > > > > >Heh, no, USB can't do DMA at all. Why would you think they could? It's > > >a serial bus that just streams data across it at relativly slow speeds. > > > > > > > Well.. even though I didn't know how and was a bit suspicious, I used > > to believe that USB devices could do DMA because I heard some time ago > > about "the danger of USB devices that could do DMA and have total > > access over the OS"... something on bugtraq or securityfocus... > > talking about USB and FireWire devices and how they could be used to > > "inject" stuff on the system's memory and take it over... but I guess > > it only applies to firewire (even though USB was clearly mentioned). > > Reviewing it, it definitely applies just for firewire stuff. > > > > http://www.csoonline.com/read/050106/ipods.html > > Yes, firewire and USB is very different. You can't dma memory directly > out using USB, although I've heard rumors that through the USB debug > port you might be able to do that, but as that requires a custom cable, > which no one will give me, I can't confirm or deny that yet... > > thanks, > > greg k-h > -- What this world needs is a good five-dollar plasma weapon.