Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965162Ab2JXL1O (ORCPT ); Wed, 24 Oct 2012 07:27:14 -0400 Received: from casper.infradead.org ([85.118.1.10]:59220 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964954Ab2JXL1N (ORCPT ); Wed, 24 Oct 2012 07:27:13 -0400 Subject: Re: [PATCHv3 5/7] dmaengine: dw_dmac: add PCI part of the driver From: Vinod Koul To: Viresh Kumar Cc: vinod.koul@intel.com, Andy Shevchenko , Arnd Bergmann , linux-kernel@vger.kernel.org, spear-devel , Heikki Krogerus In-Reply-To: References: <1348731121-2515-1-git-send-email-andriy.shevchenko@linux.intel.com> <1348731121-2515-6-git-send-email-andriy.shevchenko@linux.intel.com> <1348735450.1648.5.camel@vkoul-udesk3> <1348739022.13371.157.camel@smile> <1348740071.1648.25.camel@vkoul-udesk3> <1349691428.10584.95.camel@smile> <1349700409.10584.118.camel@smile> Content-Type: text/plain; charset="UTF-8" Date: Wed, 24 Oct 2012 16:43:38 +0530 Message-ID: <1351077218.5263.62.camel@vkoul-udesk3> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1659 Lines: 37 On Mon, 2012-10-08 at 18:57 +0530, Viresh Kumar wrote: > I agree that there are some parts of your approach which might be having > few advantages. But it is actually adding more complexity without much > need of it. Logically speaking, we never had two devices for the same > dma controller. We are adding them just to have pci over platform.. Which > would mean the system become more and more complex.. > > So, during run time... > - there will be two device-driver binding loops.. Once for pci and then for > platform > - In suspend/resume... two devices will get into suspend, instead of one.. > - There might be other frameworks in kernel.. which react on struct device > basis... they will get affected too.. > - You have larger image size for pci case. as you compile platform too.. > > Just try to think from this perspective... we dont have two hardware devices > in the system.... Ideally speaking there must be a struct device associated > with a hardware device... > > @Arnd/Vinod: Can you guys throw some more light here.. on the adv/disadv > of both the approaches? I am worried about those tow. Runtime PM handlers in case PCI devices make life a lot easier am not sure what support will be there for platform devices in other systems. Also next version of this h/w on our systems is bringing subtle changes so having them separate seemed to me a better idea. -- Vinod Koul Intel Corp. -- 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/