From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753202Ab0C2UUx (ORCPT ); Mon, 29 Mar 2010 16:20:53 -0400 Received: from mail-gx0-f217.google.com ([209.85.217.217]:57653 "EHLO mail-gx0-f217.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751045Ab0C2UUw convert rfc822-to-8bit (ORCPT ); Mon, 29 Mar 2010 16:20:52 -0400 MIME-Version: 1.0 In-Reply-To: <201003292304.39657.temerkhanov@yandex.ru> References: <201003172118.41559.temerkhanov@cifronik.ru> <1269877373.6173.27.camel@iscandar.digidescorp.com> <201003292304.39657.temerkhanov@yandex.ru> From: Grant Likely Date: Mon, 29 Mar 2010 14:20:31 -0600 X-Google-Sender-Auth: 6374b2801e37a262 Message-ID: Subject: Re: [PATCH] [RFC] Xilinx MPMC SDMA subsystem To: Sergey Temerkhanov Cc: linuxppc-dev@lists.ozlabs.org, steve@digidescorp.com, microblaze-uclinux@itee.uq.edu.au, Sergey Temerkhanov , Linux Kernel Mailing List Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 29, 2010 at 1:04 PM, Sergey Temerkhanov wrote: > On Monday 29 March 2010 19:56:15 Grant Likely wrote: >> On Mon, Mar 29, 2010 at 9:42 AM, Steven J. Magnani >> >> wrote: >> > On Fri, 2010-03-26 at 17:53 -0600, Grant Likely wrote: >> >> I've not got time to review this patch right now, but Sergey and >> >> Steven, you both posted MPMC drivers on the same day; Steven on the >> >> microblaze list and Sergey on the powerpc list. šCan you two please >> >> coordinate and figure out how to mork toward a single driver that will >> >> meet both your needs? šI don't want to have 2 drivers (3 if you count >> >> the ll_temac driver) in mainline for the same hardware interface. >> > >> > I don't think we'll end up with a single driver. A MPMC DMA Engine >> > driver is useful only on "loopback" SDMA ports. Sergey's code looks like >> > a nice generic interface to Xilinx SDMA HW that could be used by the >> > xlldma and ll_temac drivers, for instance. Both of those will get >> > smaller, but won't go away. > > Yes, it's like having IBM EMAC driver and MAL layer or something > >> > >> > For this to be useful to me, it would need to be located somewhere more >> > accessible than arch/powerpc and it would need to have initialization >> > methods that don't depend on OF. In my build I would have platform code >> > that binds to the xlldma platform attachment, which would call Sergey's >> > SDMA code to assign it the proper resources. >> >> That should be fine. > > Well, I'll look at my old code for the platform interface bindings. I remember > it worked well on arch/ppc with my other drivers. Don't get too caught up in this aspect. of_platform_bus_type is being merged with platform_bus_type. One driver can be written to handle both use cases. However, it may not make any sense for the DMA library layer to have a bus binding since it is mostly a set of shared routines. I'm fine if the bindings are only at the SDMA driver and ll_temac driver level. g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.