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=-4.2 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, USER_AGENT_SANE_1 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 70EE9C433E0 for ; Thu, 4 Mar 2021 04:41:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FD0164EDF for ; Thu, 4 Mar 2021 04:41:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233510AbhCDElM (ORCPT ); Wed, 3 Mar 2021 23:41:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233529AbhCDEk5 (ORCPT ); Wed, 3 Mar 2021 23:40:57 -0500 Received: from mail-pj1-x102b.google.com (mail-pj1-x102b.google.com [IPv6:2607:f8b0:4864:20::102b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1AA83C061574 for ; Wed, 3 Mar 2021 20:40:17 -0800 (PST) Received: by mail-pj1-x102b.google.com with SMTP id i4-20020a17090a7184b02900bfb60fbc6bso3952198pjk.0 for ; Wed, 03 Mar 2021 20:40:17 -0800 (PST) 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:content-transfer-encoding:in-reply-to :user-agent; bh=SpcbDVmRqFNq4jiEcFBJPIdb5VQK/AyECyUcyP3VJwQ=; b=cgCTgg+yYRnpBZDy0oDzkLb//gOYIdp8+nQx/9ooEMrFvyMJufQ+vlDaVKjijG6aKE m7mUqx+drfhvvf/lz0D7NFURHAUlwdQEfD+yY8eU283fW66ya16kbkQ3Fq1ukiaJo4Zz gc/uc3DJRJ0JUVpGawj2V1KKBergXel0quuRDi1AcCqf6PuCNRHKjFwSfJp1+L+S8iGe OZt1wxiNim1yDBcRCj4ylXS3NefPgrVeNs27bUNHAWXCLk1RV7EgTbX6Iv+o3ERJp1Ms W2suK/sMv7TX/g96VC584bFqbUW5DUWJXtB00SHxoNtZ7CtNViujyoPWp26aDJANiteF 4yxA== 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:content-transfer-encoding :in-reply-to:user-agent; bh=SpcbDVmRqFNq4jiEcFBJPIdb5VQK/AyECyUcyP3VJwQ=; b=iKX/o64YJz88eh2cPA6QZDjUxDaTO7vpjE5nLyrSlHLozmVvdoHlX7M+nW56D4mMEo ayEJEa+WCP8zz6j7TZGyl6Mue2Z34x8vgjo41zXUBpK9w/G70JW7vCvOXsC0yBdBXUF2 uDwoiDck+7oSsAZxquaLZiY/nHfZMudXmVnM1hLDtsNqH4K2pk7pdMX7YPKD7iwokd8m ZNP1rWteZKm6sKVS/gzY/IH+dppPvPB6P2u1bNVhr6VgshYxYsO5Zf+liAVIte0e4ahS QNwiDF+rXahY9SbeUdiy0N7IEjmShn1vJPnBvygaVVFt9oKEXzeFAXzgspYepclRQ4XD quLg== X-Gm-Message-State: AOAM5330cU+1a2OjwC2I0Kp0354+rMaKijBSgB+xPPG+JuDuF4OEg8VV AVePlCA+A+r0jMGWILb+rl0= X-Google-Smtp-Source: ABdhPJwhOKsR/a60si2IPq8i8t4IcatCnyOb2OuEU/EaMDW5qGVaoNv41iz2vgYEhZ492USuhfV92g== X-Received: by 2002:a17:902:b609:b029:e3:4b8d:994 with SMTP id b9-20020a170902b609b02900e34b8d0994mr2271643pls.44.1614832816621; Wed, 03 Mar 2021 20:40:16 -0800 (PST) Received: from localhost ([211.108.35.36]) by smtp.gmail.com with ESMTPSA id z16sm24415051pgj.51.2021.03.03.20.40.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Mar 2021 20:40:16 -0800 (PST) Date: Thu, 4 Mar 2021 13:40:13 +0900 From: Minwoo Im To: Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= Cc: linux-pci@vger.kernel.org, Bjorn Helgaas Subject: Re: [PATCH] PCI: Take __pci_set_master in do_pci_disable_device Message-ID: <20210304044013.GA15757@localhost.localdomain> References: <20210214110637.24750-1-minwoo.im.dev@gmail.com> <20210215132220.GA32476@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 21-02-24 23:46:00, Krzysztof Wilczyński wrote: > Hi Minwoo, > > Sorry for a very late reply! > > [...] > > > You might need to improve the subject a little - it should be brief but > > > still informative. > > > > > > > __pci_set_mater() has debug log in there so that it would be better to > > > > take this function. So take __pci_set_master() function rather than > > > > open coding it. This patch didn't move __pci_set_master() to above to > > > > avoid churns. > > > [...] > > > > > > It would be __pci_set_master() in the sentence above. Also, perhaps > > > "use" would be better than "take". Generally, this commit message might > > > need a little improvement to be more clear why are you do doing this. > > > > Sure, if we consolidate bus master enable clear functions to a single > > one, it would be better to debug and tracing the kernel behaviors. > > > > Let me describe this 'why' to the description. > > Sounds great! Thank you! > > [...] > > > You could use pci_clear_master(), which we export and that internally > > > calls __pci_set_master(), so there would be no need to add any forward > > > declarations or to move anything around in the file. > > > > Moving delcaration to above might be churn, and I agree with your point. > > I am sure that when it makes sense, then probably folks would not > object, especially since "churn" can be subjective. > > > > Having said that, there is a difference between do_pci_disable_device() > > > and how __pci_set_master() works - the latter sets the is_busmaster flag > > > accordingly on the given device whereas the former does not. This might > > > be of some significance - not sure if we should or should not set this, > > > since the do_pci_disable_device() does not do that (perhaps it's on > > > purpose or due to some hisoric reasons). > > > > Thanks for pointing out this. I think the difference about > > `is_busmaster` flag looks like it should not be cleared in case of power > > suspend case: > > > > # Suspend > > pci_pm_default_suspend() > > pci_disable_enabled_device() > > > > # Resume > > pci_pm_reenable_device() > > pci_set_master() <-- This is based on (is_busmaster) > > > > > > Please let me know if I'm missing here, and appreciate pointing that > > out. Maybe I can post v2 patch with add an argument of whether > > `is_busmaster` shoud be set inside of the function or not to > > __pci_set_master()? > [...] > > Nothing is ever simple, isn't it? :-) > > We definitely need to make sure that PM can keep relying on the > is_busmaster flag to restore bus mastering to previous state after the > device would resume after being suspended. Yes, > If we add another boolean argument, then we would need to update the > __pci_set_master() only in two other places, aside of using it in the > do_pci_disable_device() function, as per (as of 5.11.1 kernel): I agree with this approach. I can try it by adding another bool argument to decide whether to update the is_busmaster flag or not inside of the __pci_set_master. > > File Line Content > drivers/pci/pci.c 4308 __pci_set_master(dev, true); > drivers/pci/pci.c 4319 __pci_set_master(dev, false); > > This is not all that terrible, provided that we _really_ do want to > change this function signature and then add another condition inside. > > What do you think? If you still like the idea, then send second version > over with all the other proposed changes. Let me prepare the next version of this patch. Thanks! > Krzysztof