From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [PATCH RFC 1/1] ASoC: fsl_ssi: Make fifo watermark and maxburst settings device tree options Date: Thu, 14 Jan 2016 21:25:39 -0600 Message-ID: <20160115032539.GA26909@rob-hp-laptop> References: <1452788982-11583-1-git-send-email-caleb@crome.org> <20160114201858.GA17567@Asurada-Nvidia> <56984BE7.2050303@tabi.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by alsa0.perex.cz (Postfix) with ESMTP id F1AB626052B for ; Fri, 15 Jan 2016 04:25:44 +0100 (CET) Content-Disposition: inline In-Reply-To: <56984BE7.2050303@tabi.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Timur Tabi Cc: devicetree@vger.kernel.org, alsa-devel@alsa-project.org, Xiubo Li , linux-kernel@vger.kernel.org, Takashi Iwai , Liam Girdwood , Caleb Crome , Nicolin Chen , Mark Brown List-Id: alsa-devel@alsa-project.org On Thu, Jan 14, 2016 at 07:31:19PM -0600, Timur Tabi wrote: > Nicolin Chen wrote: > >I think DT maintainers may not give a consent towards these two > >properties as they are not to describe the hardware but to hack > >software configurations. (And it seems you haven't CCed them.) > > I admit it's a grey area, but the hardware doesn't work if you use the wrong > value, and it is a fixed value per device. A p1022ds would use a different > value than in in i.MX6, and once you pick a value, it's the same no matter > which sample rate, buffer size, etc you choose. We've allowed similar properties for other things like SPI controllers. It really depends on the frequency you expect to change it. The more often it changes, the higher up the s/w stack it should be controlled (firmware/DT, kernel, or userspace). A function of the SOC or codec rate, then yes DT is fine. Every user needs to tune it on the same platform, then no, don't put it in DT. My recollection from i.MX is this would be the former case. Rob From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753372AbcAODZp (ORCPT ); Thu, 14 Jan 2016 22:25:45 -0500 Received: from mail.kernel.org ([198.145.29.136]:47850 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751159AbcAODZn (ORCPT ); Thu, 14 Jan 2016 22:25:43 -0500 Date: Thu, 14 Jan 2016 21:25:39 -0600 From: Rob Herring To: Timur Tabi Cc: Nicolin Chen , Caleb Crome , Xiubo Li , Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org Subject: Re: [PATCH RFC 1/1] ASoC: fsl_ssi: Make fifo watermark and maxburst settings device tree options Message-ID: <20160115032539.GA26909@rob-hp-laptop> References: <1452788982-11583-1-git-send-email-caleb@crome.org> <20160114201858.GA17567@Asurada-Nvidia> <56984BE7.2050303@tabi.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56984BE7.2050303@tabi.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 14, 2016 at 07:31:19PM -0600, Timur Tabi wrote: > Nicolin Chen wrote: > >I think DT maintainers may not give a consent towards these two > >properties as they are not to describe the hardware but to hack > >software configurations. (And it seems you haven't CCed them.) > > I admit it's a grey area, but the hardware doesn't work if you use the wrong > value, and it is a fixed value per device. A p1022ds would use a different > value than in in i.MX6, and once you pick a value, it's the same no matter > which sample rate, buffer size, etc you choose. We've allowed similar properties for other things like SPI controllers. It really depends on the frequency you expect to change it. The more often it changes, the higher up the s/w stack it should be controlled (firmware/DT, kernel, or userspace). A function of the SOC or codec rate, then yes DT is fine. Every user needs to tune it on the same platform, then no, don't put it in DT. My recollection from i.MX is this would be the former case. Rob