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 1AB97C433E6 for ; Tue, 1 Sep 2020 14:33:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E5AC920767 for ; Tue, 1 Sep 2020 14:33:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FJT3ngsL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727099AbgIAOc6 (ORCPT ); Tue, 1 Sep 2020 10:32:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43772 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728284AbgIAOWt (ORCPT ); Tue, 1 Sep 2020 10:22:49 -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 F15A4C061244; Tue, 1 Sep 2020 07:22:47 -0700 (PDT) Received: by mail-ej1-x643.google.com with SMTP id z22so1920441ejl.7; Tue, 01 Sep 2020 07:22:47 -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=KDkiB9BCvl2LEGL4AwMELN+jD38wa8iIZfBR6WIjqwI=; b=FJT3ngsLt2Vv6b+aR0Xh8VuoqaF5Wi2KdXUsoXGCOQVq9GY1loIqkkAi3QcNwf8gMD tAGWUa2x+XdcL7mFWCQW8PHImjr0QdTTGoNc2eu9mFGLJ4ADDVl7s2bgfWMIydh1Mvfd Jbw7k75r1urb6b5zPVL9FdzLc0W2soApTLnspqh1wE4+/OKGxK6MWFv44RM2ttDLlKdb sY/w84yAFuDU2MYgA0WlGiapeUfvRUrgfJOJgtpwYciLCC05DbnMcScwdS1rPZaoWK4Z 3wLWNTWWe67L9knRvB+Q1aadQznzY4lL8nO1woKV6lTWen3s470TRPwRX7XF7kmpm8sB UMrg== 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=KDkiB9BCvl2LEGL4AwMELN+jD38wa8iIZfBR6WIjqwI=; b=eDpD8HJqAAF1sdAFECE8ZHI0A4J9NYBA9Ifj/+TR9QuF73tXOdhGwtPA3TNBSFFFaw Jqk/PHtZPSFYWMHLE66bwRKbHwblV8R0DwKK507lNHK7aKyyOP6CwKPdiGKVidlSGsuS r654xM8IpD5qY/vnxhNMbpEcFZY6WtMLljLfSxPU11YykKsS+DAavCg4ICkm15+JE1Nd ZD+jOMKHmrjAisdPxHKbDGPs1+pu5f80Z2zcqyObnChDbh/0EdVakdwhQDv2hOmr2UU9 +Vs8+X0jVyclsZPm+6K52uERiLyXvqXdZ9EKmueMgh18OrLZ5F2yDdMtUcieLvA8SY/N r3AA== X-Gm-Message-State: AOAM533cDdsPWWknRgCDSXhNT7MS3Nc5n64V3avnYK53ClOIF7ozNoPa Nd3FqmOw8dvLXSUuBs912+gf5XR6Yvs= X-Google-Smtp-Source: ABdhPJzdzr6EGQ1iSKBuQLY3/jYf29synEUyluYJ1F4lvs1Nmo/VcaXazws3aQk3D6mF14U++m7+NQ== X-Received: by 2002:a17:907:7215:: with SMTP id dr21mr1858191ejc.68.1598970166353; Tue, 01 Sep 2020 07:22:46 -0700 (PDT) Received: from skbuf ([86.126.22.216]) by smtp.gmail.com with ESMTPSA id v17sm1444431ejj.55.2020.09.01.07.22.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Sep 2020 07:22:45 -0700 (PDT) Date: Tue, 1 Sep 2020 17:22:43 +0300 From: Vladimir Oltean To: Kurt Kanzenbach Cc: Andrew Lunn , Vivien Didelot , Florian Fainelli , "David S. Miller" , Jakub Kicinski , netdev@vger.kernel.org, Rob Herring , devicetree@vger.kernel.org, Sebastian Andrzej Siewior , Richard Cochran , Kamil Alkhouri , ilias.apalodimas@linaro.org Subject: Re: [PATCH v4 2/7] net: dsa: Add DSA driver for Hirschmann Hellcreek switches Message-ID: <20200901142243.2jrurmfmh6znosxd@skbuf> References: <20200901125014.17801-1-kurt@linutronix.de> <20200901125014.17801-3-kurt@linutronix.de> <20200901134020.53vob6fis5af7nig@skbuf> <87y2ltegnd.fsf@kurt> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87y2ltegnd.fsf@kurt> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Sep 01, 2020 at 04:05:42PM +0200, Kurt Kanzenbach wrote: > Hi Vladimir, > > On Tue Sep 01 2020, Vladimir Oltean wrote: > > Hi Kurt, > > > > On Tue, Sep 01, 2020 at 02:50:09PM +0200, Kurt Kanzenbach wrote: > [snip] > >> +struct hellcreek { > >> + const struct hellcreek_platform_data *pdata; > >> + struct device *dev; > >> + struct dsa_switch *ds; > >> + struct hellcreek_port *ports; > >> + struct mutex reg_lock; /* Switch IP register lock */ > > > > Pardon me asking, but I went back through the previous review comments > > and I didn't see this being asked. > > It was asked multiple times, why there was a spinlock without interrupts > being registered (see e.g. [1], [2]). I've used the spinlock variant, > because the previously used hrtimers act like interrupts. As there are > no timers anymore, there's no need for spinlocks and mutexes can be > used. > That, yes, I remember, but not why the reg_lock exists in the first place. > Florian Fainelli also asked if the reg lock can be removed > completely. See below. > Missed your answer on that. > > > > What is the register lock protecting against, exactly? > > A lot of the register operations work by: > > * Select port, priority, vlan or counter > * Configure it > > These sequences have to be atomic. That's what I wanted to ensure. > So, let me rephrase. Is there any code path that is broken, even if only theoretically, if you remove the reg_lock? > Thanks, > Kurt > > [1] - https://lkml.kernel.org/netdev/def49ff6-72fe-7ca0-9e00-863c314c1c3d@gmail.com/ > [2] - https://lkml.kernel.org/netdev/20200624130318.GD7247@localhost/ Thanks, -Vladimir