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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 44907C64EB8 for ; Thu, 4 Oct 2018 10:30:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F08B72098A for ; Thu, 4 Oct 2018 10:30:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="b2dm0exD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F08B72098A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727472AbeJDRXT (ORCPT ); Thu, 4 Oct 2018 13:23:19 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:40640 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727077AbeJDRXT (ORCPT ); Thu, 4 Oct 2018 13:23:19 -0400 Received: by mail-pg1-f196.google.com with SMTP id n31-v6so2954314pgm.7; Thu, 04 Oct 2018 03:30:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=DIrB1GFmPaUBymO1pImmGm1WpkpLxTjq2keCTPeUT4w=; b=b2dm0exDSD+LuLekoDzUxOqXLilQhJus9JzO2K2//rUGhRQv3WG56STzbqDjRSigxY KdTbkmYfisZ01Ljh3chs4eMED6H19q6dzps5KNF6hmek7Lbd2T00kX60Qup0tRHVk3OK oBkMuWB9dNF9z//S1Vp88vF63Emez/M2F8MHIKsn8Z8Gs8dMdTxZhDz/jkiT6i/3lIps cWZOIUvSAK6Dct4E5H1sSYHSkj62moHNiKjdcZw1qWMWC1VVbV6Mo0pEDiVYgkuaRAG3 M5J/vzNFXcRPm5KSmvHXsHpQCoyGzfrbu13iPg7nGFi5pxPTX4EZwi8BInx9gc0/YHbV JX8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=DIrB1GFmPaUBymO1pImmGm1WpkpLxTjq2keCTPeUT4w=; b=V7xxkU34z2qa+MfPE6jxKwkqmQYgtn6eGVy5YYrKWYbsjxnq9+Q2DYOz6p2xc+y3ms 26ia/dGjjnuQSqGYe2ySBz/hfmCSprDO3kxAKeNMXFUXgxUT67tKvgXh3LciOCJd0//E il+/jkSNOefYMZ7PHab3nh8pHnEnbwHCqMClBGjxNEQ7nA4Lhb2z8oew3dadXGFoRwaQ ItCbILZxN2C3tnxR2kuhs5/MNetxfzLRq8/29b/fJ/Ez4BgD3YbbmrgmRbS3ZZ5ZfR8l T2+L/b85dD/dEWFrt01sNmdaYMmRR4E3DNtuxuns/iHrBHimh5Lm1xDOn9yHYXRRYcE/ PQXw== X-Gm-Message-State: ABuFfogzBeTdnJE0BllfS20xFmdSDTudJ01ur3TeEhI/vyhSeMjbs9wq NBkKiBz5itVptM71k4PE27MkPR36 X-Google-Smtp-Source: ACcGV62z0Ra/+cRbAXfWNVb2JKRWOcKurVaM1q5FyQGVPzKQn4cVoJNrvQWrqTvtvp5IzbS0wLz1aQ== X-Received: by 2002:a63:ef53:: with SMTP id c19-v6mr5119548pgk.386.1538649040192; Thu, 04 Oct 2018 03:30:40 -0700 (PDT) Received: from icarus (122-223-50-245.fukuoka.fdn.vectant.ne.jp. [122.223.50.245]) by smtp.gmail.com with ESMTPSA id m15-v6sm11925440pfk.149.2018.10.04.03.30.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Oct 2018 03:30:39 -0700 (PDT) Date: Thu, 4 Oct 2018 19:30:28 +0900 From: William Breathitt Gray To: Andy Shevchenko Cc: Rasmus Villemoes , linus.walleij@linaro.org, akpm@linux-foundation.org, linux-gpio@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Arnd Bergmann Subject: Re: [RESEND PATCH v4 1/8] bitops: Introduce the for_each_set_clump macro Message-ID: <20181004103028.GA4779@icarus> References: <40ecad49-2797-0d30-b52d-a2e6838dc1ab@rasmusvillemoes.dk> <20181002082142.GC15943@smile.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181002082142.GC15943@smile.fi.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 02, 2018 at 11:21:42AM +0300, Andy Shevchenko wrote: > On Tue, Oct 02, 2018 at 09:42:48AM +0200, Rasmus Villemoes wrote: > > On 2018-10-02 03:13, William Breathitt Gray wrote: > > > The cover letter says > > > > The clump_size argument can be an arbitrary number of bits and is not > > required to be a multiple of 2. > > > > by which I assume you mean "power of 2", but either way, the above code > > does not seem to take into account the case where bits_offset + > > clump_size straddles a word boundary, so it wouldn't work for a > > clump_size that does not divide BITS_PER_LONG. > > E.g. 3 bits in a clump? Hmm... > > Why would we need that? I mean some real use case? GPIOs in hardware may be routed to devices logically in groups of I/O lines, yet must still be accessed via the word-sized registers on the operating machine. For example, suppose a GPIO card is used to control a set of shower devices. The card supports 4 shower devices, each device controlled by 3 lines of I/O: enable, hot-cold selection, high-low pressure selection. In this case, a operating machine would still have to access the GPIO lines via the I/O registers (e.g. 8-bit port I/O); but with a macro handling a clump size of 3-bits, we can loop logically by each shower device which is much simpler from a driver perspective. William Breathitt Gray