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=-13.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 F333EC433EF for ; Tue, 21 Sep 2021 20:52:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0D6261168 for ; Tue, 21 Sep 2021 20:52:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234622AbhIUUyT (ORCPT ); Tue, 21 Sep 2021 16:54:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232145AbhIUUyT (ORCPT ); Tue, 21 Sep 2021 16:54:19 -0400 Received: from mail-oo1-xc2b.google.com (mail-oo1-xc2b.google.com [IPv6:2607:f8b0:4864:20::c2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84CE0C061574; Tue, 21 Sep 2021 13:52:50 -0700 (PDT) Received: by mail-oo1-xc2b.google.com with SMTP id t2-20020a4ae9a2000000b0028c7144f106so119456ood.6; Tue, 21 Sep 2021 13:52:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=4uCOEvlUrcIxM24H41yB11c2ubTHQNnwRw7GlkDgvFw=; b=EUct38Lki9pNfD0k+vkv1ffBWgiByAa8zsmSxfZwvCsvk87owqSnkzSp3ocIvaQzMl rPzc/aBmdptEPGltcc5hSeHUEnaJ7RmI53woWp1dNxS+t92+ah0wRty9pdyq7Os9QCCh vIPAa9zrQHDumDbNkkcvsOzgYpbPTA775+Ko7XA+PYhYN8Ege6yV8W3pbkOsoO0YWXNI spx5ZNy5CaMDcX5W575XhYlLvXmyxzfTDclMmg102RTVS3fEWASk/BZNxMXzHUpaDKSm u9IubN3amxrEtnDWsHSw8P2HvV4ejV9VE5by6SccDKCdObYBQxzHWV+ULgpLiSpqKLHm V/bg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=4uCOEvlUrcIxM24H41yB11c2ubTHQNnwRw7GlkDgvFw=; b=6YFc851RuDOMIBxisHQb52Koqqvez5RW3Gv9FBCOLgqa5nR/Qb/ZDaKRoej/K5fUUJ R497LW42ulVo6us70NdGjWne5d9DRqWrFGTHOOvhH9RC/ytrwvtFC+cOZB3KZCuyRWzV /Jg/V7w82B/7C4vtP+Ln3hB4bP5vOuKfTwuGLQlfMqbmYx7/F01IVKQB/kVXAgY37RcH hlYA0ylcB2VUqk4adkUP5YodH9hcfv6JeNWKWLMfV8AL0l39KyixL9F35HasY79PrtMd da5AkkVYSPz00I/TMHqjuJjHZ2jHRdKg+Ncfm7pJjU4WAoEu1rVxTzCBaxMPoZuWLHOV lirw== X-Gm-Message-State: AOAM5301bR3EMsDoPFSwY2ZhxkFIioGEocxLa6QtSjwnTuEh5XdkdHzU aHhha77Nkc+fDcKpSzpRXnomhqwrxVI= X-Google-Smtp-Source: ABdhPJyS+80AhrIVGPl4b3zIAU2nYGnfMtdLmrreb9/adrxzC+pEHzwlDIpgPyFpsFFXE7nO4CYCoQ== X-Received: by 2002:a4a:7452:: with SMTP id t18mr25813466ooe.20.1632257569802; Tue, 21 Sep 2021 13:52:49 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id q17sm24395otc.28.2021.09.21.13.52.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Sep 2021 13:52:49 -0700 (PDT) Sender: Guenter Roeck Date: Tue, 21 Sep 2021 13:52:47 -0700 From: Guenter Roeck To: Rob Herring Cc: Krzysztof Adamski , Jean Delvare , Linux HWMON List , devicetree@vger.kernel.org, Oskar Senft Subject: Re: [PATCH 8/8] dt-bindings: hwmon: allow specifying channels for tmp421 Message-ID: <20210921205247.GA2363535@roeck-us.net> References: <12984255aac11a3edfc0e6278e1a1cac70ce97ec.1631021349.git.krzysztof.adamski@nokia.com> <20210921125831.GB1864238@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Tue, Sep 21, 2021 at 02:06:18PM -0500, Rob Herring wrote: > On Tue, Sep 21, 2021 at 7:58 AM Guenter Roeck wrote: > > > > On Mon, Sep 20, 2021 at 05:24:09PM -0500, Rob Herring wrote: > > > On Tue, Sep 07, 2021 at 03:46:14PM +0200, Krzysztof Adamski wrote: > > > > Add binding description for the per temperature channel configuration > > > > like labels and n-factor. > > > > > > > > Signed-off-by: Krzysztof Adamski > > > > --- > > > > .../devicetree/bindings/hwmon/tmp421.yaml | 66 +++++++++++++++++++ > > > > 1 file changed, 66 insertions(+) > > > > > > I'd keep this separate... > > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/hwmon/tmp421.yaml b/Documentation/devicetree/bindings/hwmon/tmp421.yaml > > > > index 53940e146ee6..56085fdf1b57 100644 > > > > --- a/Documentation/devicetree/bindings/hwmon/tmp421.yaml > > > > +++ b/Documentation/devicetree/bindings/hwmon/tmp421.yaml > > > > @@ -24,12 +24,49 @@ properties: > > > > reg: > > > > maxItems: 1 > > > > > > > > + '#address-cells': > > > > + const: 1 > > > > + > > > > + '#size-cells': > > > > + const: 0 > > > > + > > > > required: > > > > - compatible > > > > - reg > > > > > > > > additionalProperties: false > > > > > > > > +patternProperties: > > > > + "^input@([0-4])$": > > > > + type: object > > > > + description: | > > > > + Represents channels of the device and their specific configuration. > > > > + > > > > + properties: > > > > + reg: > > > > + description: | > > > > + The channel number. 0 is local channel, 1-4 are remote channels > > > > + items: > > > > + minimum: 0 > > > > + maximum: 4 > > > > + > > > > + label: > > > > + description: | > > > > + A descriptive name for this channel, like "ambient" or "psu". > > > > + > > > > + n-factor: > > > > > > ti,n-factor > > > > n-factor isn't just supported by TI sensors, though it isn't always called > > n-factor. Maxim (eg MAX6581) uses the term "ideality factor", though they > > also refer to the factor as "N" in the datasheet. > > > > So question is if we make this ti,n-factor and maxim,n-factor, or if we make > > it generic and define some kind of generic units. Thoughts ? My personal > > preference would be a generic definition, but is not a strong preference. > > generic if the units are generic. Though if the register value is > opaque to s/w, then maybe register value is fine. > > > In regard to units, the n-factor is, as the name says, a factor. Default > > value is 1.008. The value range for MAX6581 is 0.999 to 1.030. For TMP421 > > it is 0.706542 to 1.747977. So the scondary question is if the value > > written should be the register value (as proposed here) or the absolute > > factor (eg in micro-units). > > A range, but the register value can only be 0 or 1? > No, register values are 0x0 .. 0x1f for MAX6581, and 0x0 .. 0xff for TMP421. > > > > > > > > Needs a type reference too. > > > > > > > + description: | > > > > + The value (two's complement) to be programmed in the channel specific N correction register. > > > > + For remote channels only. > > > > + items: > > > > + minimum: 0 > > > > + maximum: 1 > > > > + > > > > + required: > > > > + - reg > > > > + > > > > + additionalProperties: false > > > > + > > > > examples: > > > > - | > > > > i2c { > > > > @@ -41,3 +78,32 @@ examples: > > > > reg = <0x4c>; > > > > }; > > > > }; > > > > + - | > > > > + i2c { > > > > + #address-cells = <1>; > > > > + #size-cells = <0>; > > > > + > > > > + sensor@4c { > > > > + compatible = "ti,tmp422"; > > > > + reg = <0x4c>; > > > > + #address-cells = <1>; > > > > + #size-cells = <0>; > > > > + > > > > + input@0 { > > > > + reg = <0x0>; > > > > + n-factor = <0x1>; > > > > + label = "local"; > > > > + }; > > > > In the context or other sensors, question here is if we can make the > > bindings generic. We have been discussing this for NCT7802Y. The main > > question for me is how to handle different sensor types. TMP421 is > > easy because it only has one type of sensors, but there are other > > devices which also have, for example, voltage and/or current sensors. > > NCT7802 is an example for that. We just had a set of bindings for that > > chip proposed at > > https://patchwork.kernel.org/project/linux-hwmon/patch/20210921004627.2786132-1-osk@google.com/ > > > > Would it be possible to determine a generic scheme that works for all > > chips ? I can see two problems: > > - How to express sensor types. The NCT7802 submission proposes another level > > of indirection, ie > > > > temperature-sensors { > > > > + > > > > + input@1 { > > > > + reg = <0x1>; > > > > + n-factor = <0x0>; > > > > + label = "somelabel"; > > > > + }; > > > > + > > > > + input@2 { > > > > + reg = <0x2>; > > > > + status = "disabled"; > > > > + }; > > > > + }; > > > > + }; > > }; > > I think the function should be within the node. Otherwise, the > addressing becomes weird (e.g. input@3 is under current-sensors or > something) with seemingly separate address spaces. > Sorry, can you translate that for a DT non-expert ? Or, in other words, how would / should one express a chip with sets of, say, current-sensors, voltage sensors, and temperature sensors. Each would have a different number of channels and different parameters. > > The second question is how to express sensor index. One option is the solution > > suggested here, ie to use reg=<> as sensor index. The second is the solution > > suggested in the 7802 bindings, where the (chip specific) name is used as > > sensor index. > > > > + temperature-sensors { > > + ltd { > > + status = "disabled"; > > + }; > > + > > + rtd1 { > > + status = "okay"; > > + type = <4> /* thermistor */; > > 'type' is a bit generic. We don't want the same property name to > possibly have multiple definitions. > How about sensor-type ? > > + }; > > + }; > > > > I personally don't have a strong opinion either way, but I would like to see > > a single solution for all sensor chips. > > > > Rob, do you have a preference ? > > If it is how you address an instance of something which seems to be > the case here, then 'reg' should be used. > Ok. Thanks, Guenter