From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_NONE,T_DKIMWL_WL_HIGH autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id C0EF87D2EF for ; Tue, 4 Jun 2019 18:59:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726454AbfFDS76 (ORCPT ); Tue, 4 Jun 2019 14:59:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:55642 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725933AbfFDS76 (ORCPT ); Tue, 4 Jun 2019 14:59:58 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 458772075C; Tue, 4 Jun 2019 18:59:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559674796; bh=uvYr9y795CB2JbwLDOLLSFyo7CtJ+vrRxdMfI4yHzG4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=xmvwFQZpyLqjD98Fwe1XolN33As8tCJH1wc3K0RgCqxD2bX5JANLRJirJWgB3YKLN zp1mKSdVQ5BYt7Y/MSV94KS8/bZQQ5C4uEamwbfEXbtFJZqTVwzgDhtJMr3AxOsYRk fv1cM/fWZvBzCnbym/V0wH08jlNFTW8Fm5V89eIw= Date: Tue, 4 Jun 2019 20:59:53 +0200 From: Greg Kroah-Hartman To: Guenter Roeck Cc: Ezequiel Garcia , Enric Balletbo i Serra , linux-kernel , Gwendal Grignou , Guenter Roeck , Benson Leung , Lee Jones , kernel@collabora.com, Dmitry Torokhov , Gustavo Pimentel , Randy Dunlap , Lorenzo Pieralisi , linux-doc@vger.kernel.org, Enno Luebbers , Guido Kiener , Thomas Gleixner , Kishon Vijay Abraham I , Jonathan Corbet , Wu Hao , Kate Stewart , Tycho Andersen , Gerd Hoffmann , Jilayne Lovejoy Subject: Re: [PATCH 03/10] mfd / platform: cros_ec: Miscellaneous character device to talk with the EC Message-ID: <20190604185953.GA2061@kroah.com> References: <20190604152019.16100-1-enric.balletbo@collabora.com> <20190604152019.16100-4-enric.balletbo@collabora.com> <20190604155228.GB9981@kroah.com> <20190604183527.GA20098@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.0 (2019-05-25) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Tue, Jun 04, 2019 at 11:39:21AM -0700, Guenter Roeck wrote: > On Tue, Jun 4, 2019 at 11:35 AM Greg Kroah-Hartman > wrote: > > > > On Tue, Jun 04, 2019 at 01:58:38PM -0300, Ezequiel Garcia wrote: > > > Hey Greg, > > > > > > > > + dev_info(&pdev->dev, "Created misc device /dev/%s\n", > > > > > + data->misc.name); > > > > > > > > No need to be noisy, if all goes well, your code should be quiet. > > > > > > > > > > I sometimes wonder about this being noise or not, so I will slightly > > > hijack this thread for this discussion. > > > > > > >From a kernel developer point-of-view, or even from a platform > > > developer or user with a debugging hat point-of-view, having > > > a "device created" or "device registered" message is often very useful. > > > > For you, yes. For someone with 30000 devices attached to their system, > > it is not, and causes booting to take longer than it should be. > > > > > In fact, I wish people would do this more often, so I don't have to > > > deal with dynamic debug, or hack my way: > > > > > > diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c > > > index 4589631798c9..473549b26bb2 100644 > > > --- a/drivers/media/i2c/ov5647.c > > > +++ b/drivers/media/i2c/ov5647.c > > > @@ -603,7 +603,7 @@ static int ov5647_probe(struct i2c_client *client, > > > if (ret < 0) > > > goto error; > > > > > > - dev_dbg(dev, "OmniVision OV5647 camera driver probed\n"); > > > + dev_info(dev, "OmniVision OV5647 camera driver probed\n"); > > > return 0; > > > error: > > > media_entity_cleanup(&sd->entity); > > > > > > In some subsystems, it's even a behavior I'm more or less relying on: > > > > > > $ git grep v4l2_info.*registered drivers/media/ | wc -l > > > 26 > > > > > > And on the downsides, I can't find much. It's just one little line, > > > that is not even noticed unless you have logging turned on. > > > > Its better to be quiet, which is why the "default driver registration" > > macros do not have any printk messages in them. When converting drivers > > over to it, we made the boot process much more sane, don't try to go and > > add messages for no good reason back in please. > > > > dynamic debugging can be enabled on a module and line-by-line basis, > > even from the boot command line. So if you need debugging, you can > > always ask someone to just reboot or unload/load the module and get the > > message that way. > > > > Can we by any chance make this an official policy ? I am kind of tired > having to argue about this over and over again. Sure, but how does anyone make any "official policy" in the kernel? :) I could just go through and delete all "look ma, a new driver/device!" messages, but that might be annoying... thanks, greg k-h