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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 F26CDC55185 for ; Sat, 25 Apr 2020 11:43:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF13320724 for ; Sat, 25 Apr 2020 11:43:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FBGpWRsh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726121AbgDYLns (ORCPT ); Sat, 25 Apr 2020 07:43:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43512 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726061AbgDYLns (ORCPT ); Sat, 25 Apr 2020 07:43:48 -0400 Received: from mail-pg1-x544.google.com (mail-pg1-x544.google.com [IPv6:2607:f8b0:4864:20::544]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 04857C09B04B; Sat, 25 Apr 2020 04:43:48 -0700 (PDT) Received: by mail-pg1-x544.google.com with SMTP id o15so5976240pgi.1; Sat, 25 Apr 2020 04:43:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=D+fcBxNw/nwKWvas8bdh9z7lSOeFbVCVoSvS/R8YOZ4=; b=FBGpWRshuMLAD0L8sCwi1qBFiM3qU3inaSks+NHjc7EiO83P6aGntSbE2m7YDKbG5A mryVIOJddS5k0MIvthi5ILVpua11o+xn4uZLMq8u/ZsXyoJdqK7bAoMKNIIY1NIhwtjc 1z/odHsWWdDINScg3E4/CyJ/AeQD6xWnmEf1GbZDkkZgfQIOZUjuhtp5RAZt9wmJHGWA +eAC9LSaIca26xLroqp+HQms8+mbdhBXjranbaNt38IMGkBTgiAUHmMXaawGs+el9fC8 KdkTEEUa7+dBq/A+o0nAoHaZqtVIK2LyuytNm7vxyBqOcHRxETVHUaZu1USwsNuT/sx/ DBiA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=D+fcBxNw/nwKWvas8bdh9z7lSOeFbVCVoSvS/R8YOZ4=; b=Xt5ya8mSHJ4Jmt4u4UFcova67qDqusn2rIoEEKin7zOIPxtXP0eouMsyjFWwVzAx9d Smv+kxOHcn7WqWpHq3i01mGkCyAZfE1w7Fbj2Bp6I1kqkc6j/O2TwwW8Y85RpeQ3QNzT xdl+K8WBDiwklYrgwFWWA7WKtyoyJ54vdbhUZdzxNn3aDJSSHpFJkhTEbPKHUYanBrd2 wCQi7kLP3iCHej3nbR9wdYuCYU2eyzvRmPDPQ/HgxUZrkldXBnrhB0/wNJ0BiapcpaCD LZzeE50Jqpeld3NhCfOTzDfVWyISIMm8Ybe+cCOQ5Yq0saxJ4LLrqcals5vTbPrDTB6e yvwg== X-Gm-Message-State: AGi0PuZDP9MGLJM4YRE7tM6utd5mhyqVNXwxq4+WMqidJzYmTrI9N9d3 GPxvkwYICAvdZJcJgB9HYfK+pt7eeumWC8ezObdB8syNrJQ= X-Google-Smtp-Source: APiQypLNRmDFDdkqQqFUJOEj14NHuHK26wddSprK6QKYDfBaSBDQ4d1J6m87q/0nL6ioabJ60J0w18/POeBEdQJoJGI= X-Received: by 2002:a62:5ec7:: with SMTP id s190mr14036650pfb.130.1587815027309; Sat, 25 Apr 2020 04:43:47 -0700 (PDT) MIME-Version: 1.0 References: <20200422141135.86419-1-tomasz.duszynski@octakon.com> <20200422141135.86419-2-tomasz.duszynski@octakon.com> <20200424190413.GA2731@arch> In-Reply-To: <20200424190413.GA2731@arch> From: Andy Shevchenko Date: Sat, 25 Apr 2020 14:43:35 +0300 Message-ID: Subject: Re: [PATCH 1/6] iio: chemical: scd30: add core driver To: Tomasz Duszynski Cc: linux-iio , Linux Kernel Mailing List , devicetree , Rob Herring , Jonathan Cameron Content-Type: text/plain; charset="UTF-8" Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Fri, Apr 24, 2020 at 10:05 PM Tomasz Duszynski wrote: > On Wed, Apr 22, 2020 at 10:49:44PM +0300, Andy Shevchenko wrote: > > On Wed, Apr 22, 2020 at 5:22 PM Tomasz Duszynski > > wrote: ... > > > Add Sensirion SCD30 carbon dioxide core driver. > > > > And DocLink tar of Datasheet: with a link? > > I never do this. These files change their location way too often to be > worthwhile putting here. Nobody has that much time to fallow all this > and keep respective files up to date. > > But that doesn't mean I can't drop a link here. > https://developer.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/9.5_CO2/Sensirion_CO2_Sensors_SCD30_Interface_Description.pdf Yes, just make it a tag DocLink: .... ... > > > +int scd30_probe(struct device *dev, int irq, const char *name, void *priv, > > > + int (*command)(struct scd30_state *state, enum scd30_cmd cmd, > > > + u16 arg, char *rsp, int size)); > > > > My gosh. > > Please, supply proper structure member in priv or alike. > > Not sure it's worth the fuss. Wrapping all into structure means either > copying respective members or more dereferences later on. At least you may introduce a typedef, because above really hurts my eyes. ... > > > +enum { > > > + CONC, > > > + TEMP, > > > + HR, > > > +}; > > > > Way too generic names for anonymous enum. > > I'd argue that they are pretty well understood abbreviations in iio generally > and here specifically. But adding some prefix won't harm. Yes, prefix is what I was talking about. ... > > > +static int scd30_wait_meas_poll(struct scd30_state *state) > > > +{ > > > + int tries = 5; > > > + > > > + while (tries--) { > > > + int ret; > > > + u16 val; > > > + > > > + ret = scd30_command(state, CMD_MEAS_READY, 0, (char *)&val, > > > + sizeof(val)); > > > + if (ret) > > > + return -EIO; > > > + > > > + /* new measurement available */ > > > + if (val) > > > + break; > > > + > > > + msleep_interruptible(state->meas_interval * 250); > > > + } > > > + > > > + if (tries == -1) > > > + return -ETIMEDOUT; > > > > unsigned int tries = ...; > > > > do { > > ... > > } while (--tries); > > if (!tries) > > return ...; > > > > looks better and I guess less code in asm. > > > > You mean that one extra branch in case of while? There are few things: a) do {} while notation immediately tells that at least one cycle of body will be done (unconditionally); b) it makes a loop variable unsigned and no need to check for specific negative numbers; c) it quite likely will generate slightly better assembly code. > But it comes to code > itself it looks more compact. And I am okay with that. > > > > + return 0; > > > +} ... > > > + if (kstrtou16(buf, 0, &val)) > > > + return -EINVAL; > > > > Shadowed error code. Don't do like this. > > Integer parsing either returns EINVAL or ERANGE. Passing the latter to > the user is not worth the trouble, especially because majority of writable attrs > have a fellow _available attr. It's simple a bad coding practice. Please, change. > > > + if (kstrtou16(buf, 0, &val)) > > > + return -EINVAL; > > > > Ditto. > > > > > + if (kstrtou16(buf, 0, &val)) > > > + return -EINVAL; > > > > Ditto. ... > > > + if (kstrtou16(buf, 0, &val)) > > > + return -EINVAL; > > > > No shadowed error code, please. Check entire code. Same here. ... > > > +static IIO_DEVICE_ATTR_RW(pressure_comp, 0); > > > +static IIO_DEVICE_ATTR_RO(pressure_comp_available, 0); > > > +static IIO_DEVICE_ATTR_RW(meas_interval, 0); > > > +static IIO_DEVICE_ATTR_RO(meas_interval_available, 0); > > > +static IIO_DEVICE_ATTR_RW(asc, 0); > > > +static IIO_DEVICE_ATTR_RW(frc, 0); > > > +static IIO_DEVICE_ATTR_RO(frc_available, 0); > > > +static IIO_DEVICE_ATTR_RW(temp_offset, 0); > > > +static IIO_CONST_ATTR(temp_offset_available, "[0 1 65535]"); > > > +static IIO_DEVICE_ATTR_WO(reset, 0); > > > > Do you need all of them? Doesn't IIO core provides a tons of helpers for these? > > Btw, where is ABI documentation? It's a show stopper. > > They are sensor specific and none falls into a category of iio generic > attrs. Maybe, except the measurement interval which could be represented as > a SAMP_FREQ. IIO ABI becomes already a big pile of nodes and I hope we will become stricter about adding new ones. > But given that measurement interval spans from 2s to 1800s > it becomes a little bit awkward to have it in Hz. > As for ABI that's in > a separate patch. It's not good from bisectability point of view. If by some reason this patch or documentation patch gets reverted, the other one will be dangling. Please, unify them. -- With Best Regards, Andy Shevchenko