From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756379Ab2ANVZL (ORCPT ); Sat, 14 Jan 2012 16:25:11 -0500 Received: from mail-bk0-f46.google.com ([209.85.214.46]:51649 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751702Ab2ANVZK (ORCPT ); Sat, 14 Jan 2012 16:25:10 -0500 Message-ID: <4F11F271.402@mvista.com> Date: Sun, 15 Jan 2012 01:24:01 +0400 From: Sergei Shtylyov User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:9.0) Gecko/20111222 Thunderbird/9.0.1 MIME-Version: 1.0 To: balbi@ti.com CC: "Gupta, Ajay Kumar" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: RFC: usb: musb: Adding CPPI4.1 DMA driver under drivers/dma References: <201201120753.00667.oneukum@suse.de> <20120112215014.GC5735@xanatos> <20120112215459.GA1161@kroah.com> <20120112222947.GD5735@xanatos> <20120112223513.GA2925@kroah.com> <20120113061144.GA30569@suse.cz> <47CEF8C4B26E8C44B22B028A650E0EA9317A6B8B@DBDE01.ent.ti.com> <4F1096E9.4020501@mvista.com> <20120113201010.GJ3133@legolas.emea.dhcp.ti.com> In-Reply-To: <20120113201010.GJ3133@legolas.emea.dhcp.ti.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello. On 14-01-2012 0:10, Felipe Balbi wrote: >>> CPPI4.1 (Communication Port Programming Interface) is a TI specific DMA >>> controller used in multiple TI platform such as AM33x, DA8x, AM35x, TI81x. >>> The DMA engine is mainly used by musb controller on above platform. >> There are (at least out of tree) platforms using CPPI 4.1 for Ethernet. > if they are out of tree, I'm sorry but we don't care about them. If they > are in tree, then that needs to be sorted out on the same patchset. I'm not sure if Puma-5 is the only one using CPPI 4.1 for Etherhet, and not some new platfroms introduced just now like AM33x/TI81x. >>> It would involve changes in existing musb driver also for which current >>> plan is to maintain the compatibility of non-CPPI4.1 DMA in musb driver. >> I didn't quite understand this part... > how come ? What he's saying is that while moving cppi-dma.c to How come we are taling of cppi-dma.c at all? It's CPPI 3.0 driver having nothing in common with CPPI 4.1. > drivers/dma he will not move all the other dma engines (Inventra, OMAP, > TUSB-over-GPMC, etc). >>> The task is planned to be spitted into below subtasks. >>> (1) Post RFC on the API details, changes envisaged in musb driver and other >>> challenges >> First of all, I foresee changes in drivers/dma/ to cope with the >> entity in CPPI 4.1 called the queue manager (there's also buffer >> manager but it wasn't implemented on DA8xx, so I didn't design any >> API for it). > that's why the kernel is open source, right ? If we need to improve the > framework so that it understands other types of DMAs, so be it. I just foresee difficulties here. WBR, Sergei