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=-3.8 required=3.0 tests=BAYES_00,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 8B8CBC433E2 for ; Sun, 30 Aug 2020 12:12:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5A6182087D for ; Sun, 30 Aug 2020 12:12:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="UsFqJfCX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726404AbgH3MMC (ORCPT ); Sun, 30 Aug 2020 08:12:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55862 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726130AbgH3MMB (ORCPT ); Sun, 30 Aug 2020 08:12:01 -0400 Received: from mail-ej1-x643.google.com (mail-ej1-x643.google.com [IPv6:2a00:1450:4864:20::643]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77905C061573; Sun, 30 Aug 2020 05:12:00 -0700 (PDT) Received: by mail-ej1-x643.google.com with SMTP id q13so1413346ejo.9; Sun, 30 Aug 2020 05:12:00 -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; bh=qshWuo/PMDUT2LJmbVBMnw6b8Zf9zlNuTmEls1ekJ0U=; b=UsFqJfCX0P9KcqTkG3XSmY1iuH1x9+PnaSu9U6Nvjs7U+EWRLwOvUb5HJ9uHPkx2uc mN5Pt5hsv1IXTgEzHKqU7hXwsatu87CTl/FxsIfWfmRxjxe4KatgxXytg4OC/G36GbUu GGSMDgk8/+OHRuAatveS9SjHVLWS1LAa7xwUo0MQN5t6Hc7rmAxtewtb8DkAawb8ek+x 2T/AvMyCvQ+NF79DFOBVCEkx+JEjTE7DXPZAGR8JS8zHjnUWptodtPW8I9TJIUg050io vpbUKkHBs6vTuRA7AxST1ivHK0GscrNxLNNBozlZ+LtOTn1ghlLYLqKerzDBHadHxFyY T4iA== 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; bh=qshWuo/PMDUT2LJmbVBMnw6b8Zf9zlNuTmEls1ekJ0U=; b=HaUH4rIDvJe0UBa9manaOgF+eW9KY/FQZJkGK/Y8WmnBmvs8YmQ99abplwm3jgtCP3 jbcDAxBZEU8RhuAYaIfqJQkWMCILf7WwwAAV+E+p2ni4h8HRuHFZLeCPCYnPyoFu4/u8 tEv0B3MxyO3yF41aqAGgbTK6P/V+G9vk5S9qKIWfbKcEo5kthQhyMGBng14Iy2IsKMfo Ms+n81mPuTe6W5vLpbEPEc/HTDQUoVlKw9gjj9tLGMFIiJASx+IYlJHWgLTHBp5iSfv0 Glk33H5IJYjfGysV9RXXsjwvJ8rzQNM5tvXkqjWLyLBioZSg9qupBIJIBCteK7TgLxPn nk7g== X-Gm-Message-State: AOAM532KTmxvbk1xebYv7ZVGSVUsDLX7hux5R/G/xuCCbke0o2q7I7Bd BUqN9M5SJKqeRFcp3O25Xf1IncgR5bo= X-Google-Smtp-Source: ABdhPJxOJA5wZn5NrOfMFMOv1nhwV+b9MWXiMCq2DdY4+4H8iKGf7KEA59WSNTM7XyEIxhZtsuU0Qw== X-Received: by 2002:a17:906:d182:: with SMTP id c2mr7289675ejz.378.1598789517357; Sun, 30 Aug 2020 05:11:57 -0700 (PDT) Received: from ltop.local ([2a02:a03f:a7fb:e200:64d5:3b87:7078:3025]) by smtp.gmail.com with ESMTPSA id bn14sm5115767ejb.115.2020.08.30.05.11.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 30 Aug 2020 05:11:56 -0700 (PDT) Date: Sun, 30 Aug 2020 14:11:54 +0200 From: Luc Van Oostenryck To: Linus Torvalds Cc: Herbert Xu , Guenter Roeck , linuxppc-dev , dma , Linux Kernel Mailing List Subject: Re: [PATCH] fsldma: fsl_ioread64*() do not need lower_32_bits() Message-ID: <20200830121154.zo54k5ywpdk2rw4m@ltop.local> References: <20200829105116.GA246533@roeck-us.net> <20200829124538.7475-1-luc.vanoostenryck@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On Sat, Aug 29, 2020 at 10:29:55AM -0700, Linus Torvalds wrote: > On Sat, Aug 29, 2020 at 5:46 AM Luc Van Oostenryck > wrote: > > > > But the pointer is already 32-bit, so simply cast the pointer to u32. > > Yeah, that code was completely pointless. If the pointer had actually > been 64-bit, the old code would have warned too. > > The odd thing is that the fsl_iowrite64() functions make sense. It's > only the fsl_ioread64() functions that seem to be written by somebody > who is really confused. > > That said, this patch only humors the confusion. The cast to 'u32' is > completely pointless. In fact, it seems to be actively wrong, because > it means that the later "fsl_addr + 1" is done entirely incorrectly - > it now literally adds "1" to an integer value, while the iowrite() > functions will add one to a "u32 __iomem *" pointer (so will do > pointer arithmetic, and add 4). > My bad. I had noticed the '+ 1' and so automatically assumed 'OK, pointer arithmetic now' without noticing that the cast was done only after the addition. Grrr. FWIW, the version you committed looks much better to me. -- Luc