From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935046AbaGYAX1 (ORCPT ); Thu, 24 Jul 2014 20:23:27 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:60961 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934483AbaGYAXZ (ORCPT ); Thu, 24 Jul 2014 20:23:25 -0400 Message-ID: <53D1A371.1000108@codeaurora.org> Date: Thu, 24 Jul 2014 17:23:13 -0700 From: Stephen Boyd User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: Linus Walleij CC: Bjorn Andersson , "Ivan T. Ivanov" , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Mark Brown , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-msm@vger.kernel.org" Subject: Re: [PATCH RESEND v2 1/4] pinctrl: Update Qualcomm pm8xxx GPIO parameters definitions References: <1405610748-7583-5-git-send-email-iivanov@mm-sol.com> <1405626085-14069-1-git-send-email-iivanov@mm-sol.com> <20140722214643.GH19700@sonymobile.com> <53D04996.2030902@codeaurora.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/24/14 08:40, Linus Walleij wrote: > On Thu, Jul 24, 2014 at 1:47 AM, Stephen Boyd wrote: > >>> Please add these constants to the table of valid power-source values and use >>> something like I did to translate them to register values - it makes the DT >>> much more readable. >> The DT could be similarly readable if we had a bunch of #defines for the >> different VIN settings that resolved to the final register value for >> that pmic. Something like PM8921_GPIO1_14_VPH, PM8921_GPIO19_36_VPH, >> etc. There would be a lot of them, but then the driver could be really >> simple and just jam whatever value is in the DT into the register >> without having to bounce through a mapping table in software to figure >> out the register value. If we did this for the functions also then I >> believe we achieve readability without requiring a bunch of drivers for >> each and every single pmic? > Not sure but it sounds like you want to make the device tree a jam table, > (know about individual register offsets, sequences etc). That has been > throrougly NACKed in the past, because DT is not Open Firmware. > > The exception is pinctrl-single which is restricted to single register > per pin use cases and is still a point of contention... > I'm not proposing a jam table. I'm proposing that we make the function/source property convenient to the driver by having the actual function field value encoded there instead of some string that has to be translated through a table in a driver. There's still going to be shifting and masking of bits in the driver to put the value in the right place in the register, but we avoid needing N number of drivers for each pmic just to translate strings into integers (for functions) and integers into other integers (for the power source). From what I can tell there isn't any benefit to having the function property be a string vs. a #define number besides having a human readable string in pinctrl debugfs. Is there some other benefit? -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation