From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8CD8ECDFB8 for ; Wed, 18 Jul 2018 05:27:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 876E520850 for ; Wed, 18 Jul 2018 05:27:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="MJP0CSkp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 876E520850 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726445AbeGRGD0 (ORCPT ); Wed, 18 Jul 2018 02:03:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:53376 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725958AbeGRGD0 (ORCPT ); Wed, 18 Jul 2018 02:03:26 -0400 Received: from localhost (unknown [106.200.213.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DE1FB20684; Wed, 18 Jul 2018 05:27:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1531891641; bh=/ieGR3d+D0SiRFYhDVh4gOFVfjw5t1O+MSo6UJUyRvE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MJP0CSkp86A84YUhy16p1GANZ81tgC/pIxNSS82dnTzfLZgr6XG+BDFySLaZHJPoZ a19u8HD+WXmiDgoG4UZlCsVONUbBkaKc2TYp7dMeCr3MzMhUshGVFNQpP4kTf2hw+N 7v0jqFZPV5wbTfkvKJTwpuHxnu7vIW/iQSSJ6+K0= Date: Wed, 18 Jul 2018 10:57:13 +0530 From: Vinod To: Rob Herring Cc: Paul Cercueil , Mark Rutland , Ralf Baechle , Paul Burton , James Hogan , Zubair Lutfullah Kakakhel , Mathieu Malaterre , Daniel Silsby , "open list:DMA GENERIC OFFLOAD ENGINE SUBSYSTEM" , devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" , Linux-MIPS Subject: Re: [PATCH 05/14] dmaengine: dma-jz4780: Add support for the JZ4740 SoC Message-ID: <20180718052713.GH3219@vkoul-mobl> References: <20180703123214.23090-1-paul@crapouillou.net> <20180703123214.23090-6-paul@crapouillou.net> <20180709171226.GK22377@vkoul-mobl> <20180716213339.GA19161@rob-hp-laptop> <20180717153407.GF3219@vkoul-mobl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17-07-18, 11:40, Rob Herring wrote: > On Tue, Jul 17, 2018 at 9:34 AM Vinod wrote: > > > > On 16-07-18, 15:33, Rob Herring wrote: > > > On Mon, Jul 09, 2018 at 10:42:26PM +0530, Vinod wrote: > > > > On 03-07-18, 14:32, Paul Cercueil wrote: > > > > > > > > > enum jz_version { > > > > > + ID_JZ4740, > > > > > ID_JZ4770, > > > > > ID_JZ4780, > > > > > }; > > > > > @@ -247,6 +248,7 @@ static void jz4780_dma_desc_free(struct virt_dma_desc *vdesc) > > > > > } > > > > > > > > > > static const unsigned int jz4780_dma_ord_max[] = { > > > > > + [ID_JZ4740] = 5, > > > > > [ID_JZ4770] = 6, > > > > > [ID_JZ4780] = 7, > > > > > }; > > > > > @@ -801,11 +803,13 @@ static struct dma_chan *jz4780_of_dma_xlate(struct of_phandle_args *dma_spec, > > > > > } > > > > > > > > > > static const unsigned int jz4780_dma_nb_channels[] = { > > > > > + [ID_JZ4740] = 6, > > > > > [ID_JZ4770] = 6, > > > > > [ID_JZ4780] = 32, > > > > > }; > > > > > > > > I feel these should be done away with if we describe hardware in DT > > > > > > The compatible property can imply things like this. > > > > So what is the general recommendation, let DT describe hardware > > including version delta or use compatible to code that in driver? > > Compatible is the version. Looking at the above, the version or ID > isn't even stable. > > > Is it documented anywhere? > > Not really. It's a judgment call generally. Maybe # of DMA channels > should be a property because that is something most controllers have. > But you really have to define the property up front, not when the 2nd > version of h/w shows up with different properties. > > To start defining guidelines, a couple of things come to mind: > > - Define properties for parameters that vary from board to board (for one SoC). > - You can't add new required properties to existing bindings, so the > not present default must work for all existing compatibles (or you > need per compatible driver data). > - Bugs/quirks/errata should be handled by compatible, not adding a > property. Because bugs should be fixable without a dtb update and only > a kernel update. Sounds good to me, thanks for the guide. -- ~Vinod