From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Ivan T. Ivanov" Subject: Re: [PATCH RESEND v2 1/4] pinctrl: Update Qualcomm pm8xxx GPIO parameters definitions Date: Fri, 25 Jul 2014 18:15:29 +0300 Message-ID: <1406301329.2475.25.camel@iivanov-dev> 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> <53D1A371.1000108@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from ns.mm-sol.com ([37.157.136.199]:52990 "EHLO extserv.mm-sol.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753382AbaGYPPu (ORCPT ); Fri, 25 Jul 2014 11:15:50 -0400 In-Reply-To: <53D1A371.1000108@codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Stephen Boyd Cc: Linus Walleij , Bjorn Andersson , 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" On Thu, 2014-07-24 at 17:23 -0700, Stephen Boyd wrote: > 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). This sounds good to me. Drawback is that we will have custom function parsing code, but I will try and see what that looks like. Thanks, Ivan > 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? >