From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 273E87D089 for ; Mon, 3 Dec 2018 12:16:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726440AbeLCMRB (ORCPT ); Mon, 3 Dec 2018 07:17:01 -0500 Received: from mail-lj1-f193.google.com ([209.85.208.193]:36740 "EHLO mail-lj1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726174AbeLCMRB (ORCPT ); Mon, 3 Dec 2018 07:17:01 -0500 Received: by mail-lj1-f193.google.com with SMTP id g11-v6so11147464ljk.3; Mon, 03 Dec 2018 04:16:10 -0800 (PST) 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=yD5iVmypOBQumLl+qGUTl1jKrrZfOHc7K3noc5twFmE=; b=ahlZCn0rZmWf+1gESuNV3uwe/N+psi/w3VccCZbh8fUfqonzcUcjGMmOr+XHsrfAZp I/7hnSdtiwigzu4ihAuiX0uaAwjhFZsWJEEOtQN+dfGOMU7z8jofDOhpVgljG+2bzbb8 HgXmK6uoGN/Uc8FyYSe/NPusbjgj1p5dGX70HduHWqhoeDlm5X9vDbGSxIhcpnREvDkS 6po9fF5TJLe6AChspds72TV71r1xGU+eSLbnBqOOlJ0fs6uJ6QBsJD5gM8fTnrXGpCYX lUHoTnJCwsCAilgdieQjwoDHYAMpp29EaoIVJdIpGfFVs32xkLAwXHuyTOEe6+BLCrFR l7nQ== X-Gm-Message-State: AA+aEWYvNJ5v3twJsh1Vcsj7a4m/fm9of08s14EwQSyQBPN/+YuuoduJ 3+WET9kxCSA44gfSQ6aJIB4= X-Google-Smtp-Source: AFSGD/V9Gq703U5if+R8Zc+VCdNkNOkpC31SbP76EShumpu2cWwKss7RdnrH21yapoPz4tXab7x5DA== X-Received: by 2002:a2e:9dcb:: with SMTP id x11-v6mr10946163ljj.158.1543839369778; Mon, 03 Dec 2018 04:16:09 -0800 (PST) Received: from localhost.localdomain ([213.255.186.46]) by smtp.gmail.com with ESMTPSA id d82sm2344923lfd.82.2018.12.03.04.16.07 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 03 Dec 2018 04:16:08 -0800 (PST) Date: Mon, 3 Dec 2018 14:16:05 +0200 From: Matti Vaittinen To: Stephen Boyd Cc: mazziesaccount@gmail.com, Jonathan Corbet , Michael Turquette , Chanwoo Choi , Krzysztof Kozlowski , Bartlomiej Zolnierkiewicz , Russell King , Andy Gross , David Brown , Andrey Smirnov , Guenter Roeck , Rob Herring , Sebastian Reichel , Lee Jones , Huang Shijie , Daniel Kurtz , Akshu Agrawal , "Rafael J. Wysocki" , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org Subject: Re: [PATCH v4 1/8] clk: clkdev/of_clk - add managed lookup and provider registrations Message-ID: <20181203121605.GC15388@localhost.localdomain> References: <154356805035.88331.16867826308376667832@swboyd.mtv.corp.google.com> <20181130105022.GA15388@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181130105022.GA15388@localhost.localdomain> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Hello Stephen & All, I created v5 where I fixed obvious issues. I'll send it in few minutes. Please note following topics: On Fri, Nov 30, 2018 at 12:50:22PM +0200, Matti Vaittinen wrote: > > On Fri, Nov 30, 2018 at 12:54:10AM -0800, Stephen Boyd wrote: > > Quoting Matti Vaittinen (2018-11-13 03:55:58) > > > > > > -int devm_of_clk_add_hw_provider(struct device *dev, > > > +static int __devm_of_clk_add_hw_provider(struct device *dev, > > > struct clk_hw *(*get)(struct of_phandle_args *clkspec, > > > void *data), > > > - void *data) > > > + struct device_node *of_node, void *data) > > > { > > > - struct device_node **ptr, *np; > > > + struct device_node **ptr; > > > int ret; > > > > > > ptr = devres_alloc(devm_of_clk_release_provider, sizeof(*ptr), > > > @@ -3906,10 +3906,9 @@ int devm_of_clk_add_hw_provider(struct device *dev, > > > if (!ptr) > > > return -ENOMEM; > > > > > > - np = dev->of_node; > > > - ret = of_clk_add_hw_provider(np, get, data); > > > + *ptr = of_node; > > > + ret = of_clk_add_hw_provider(of_node, get, data); > > > if (!ret) { > > > - *ptr = np; > > > > Why is this moved outside of the if condition? > I completely removed the local variable np and just unconditionally set > the allocated devres to point at the node (if allocation succeeded). We > could of course only do this if the provider registration succeeded and > save one assignment - but I guess I intended to remove the curly braces > and thus decided to go for one liner after if. But apparently I didn't > remove the braces O_o. Well, I can put the assignment inside the > condition if you prefer that. > > > In fact, why isn't just > > the first line in this hunk deleted and passed to this function as > > struct device_node *np? > > I am sorry but I don't quite follow your suggestion here. Do you mean we > could just pass the struct device_node *np in devres_add()? I thought > the pointer passed to devress_add() should be allocated using > devres_alloc. Can you please elaborate what you mean? I could not really spot what to fix in patched code (see below). static int __devm_of_clk_add_hw_provider(struct device *dev, struct clk_hw *(*get)(struct of_phandle_args *clkspec, void *data), struct device_node *of_node, void *data) { struct device_node **ptr; int ret; ptr = devres_alloc(devm_of_clk_release_provider, sizeof(*ptr), GFP_KERNEL); if (!ptr) return -ENOMEM; *ptr = of_node; ret = of_clk_add_hw_provider(of_node, get, data); if (!ret) devres_add(dev, ptr); else devres_free(ptr); return ret; } As far as I understand we need to allocate the ptr using devres_alloc. We also need to pass this ptr to of_clk_add_hw_provider - and we must assign our node to the *ptr. (I removed the extra braces - this change is laso included in v5 but I don't see how we should improve). Can you please explain me if you still wish to me change this further? > > > +int devm_of_clk_add_parent_hw_provider(struct device *dev, > > > + struct clk_hw *(*get)(struct of_phandle_args *clkspec, > > > + void *data), > > > + void *data) > > > +{ > > > + return __devm_of_clk_add_hw_provider(dev, get, dev->parent->of_node, > > > > I'm wondering if we can somehow auto-detect this in > > devm_of_clk_add_hw_provider() by looking for #clock-cells in the node. > > If it isn't there, then we go to the parent node and look for a > > #clock-cells property there in the DT node for that device. Does that > > make sense? Then there isn't any new API and we can attach the lifetime > > of the devm registration to the presence of the property indicating this > > is a clk controller or not. > > Huh. I don't know why but building this kind of logic in core is a bit > scary to me. I guess I can try implementing something like this - but I > am not really a fan of this. (Accidentally) omit the #clock-cells from > node and we go to parent node - I am a novice on this area but this > sounds like a potential hazard to me. I believe the driver should know > if it's properties should be in own or parent node - and if they are > not, then there should be no guessing but error. The lifetime is topic > where I would like to get information from you who know the kernel > better than I do =) But I guess the parent node is there at least as > long as the child device is alive. So for me the life time of > get-callback is more crucial - but as I said, I don't understand the > kernel in details so you probably know it better than me. But please let > me know your final take on this and I will follow the guidance =) I did not put the 'auto-detection' for provider node in the patch v5 as it really gives me bad vibes :) Maybe it is just my pessimistic nature but I do expect that problems will arise when we accidentally end up in parent node when this is not the purpose. I would rather keep this simple by adding one specific API function more - and keeping the existing API specific as well. But I can do v5 if you insist on having this auto-detection. -- Matti Vaittinen ROHM Semiconductors ~~~ "I don't think so," said Rene Descartes. Just then, he vanished ~~~