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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 9FDD1C4743D for ; Tue, 8 Jun 2021 14:49:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C33E61183 for ; Tue, 8 Jun 2021 14:49:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233586AbhFHOu7 (ORCPT ); Tue, 8 Jun 2021 10:50:59 -0400 Received: from netrider.rowland.org ([192.131.102.5]:46905 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S233576AbhFHOu6 (ORCPT ); Tue, 8 Jun 2021 10:50:58 -0400 Received: (qmail 1806040 invoked by uid 1000); 8 Jun 2021 10:49:05 -0400 Date: Tue, 8 Jun 2021 10:49:05 -0400 From: Alan Stern To: Ulf Hansson Cc: "Rafael J . Wysocki" , Linux PM , Saravana Kannan , Adrian Hunter , Tony Lindgren , Kevin Hilman , Geert Uytterhoeven , Linux ARM , Linux Kernel Mailing List Subject: Re: [PATCH v2 3/3] PM: runtime: Clarify documentation when callbacks are unassigned Message-ID: <20210608144905.GE1804083@rowland.harvard.edu> References: <20210608090250.85256-1-ulf.hansson@linaro.org> <20210608090250.85256-4-ulf.hansson@linaro.org> <20210608142325.GC1804083@rowland.harvard.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 08, 2021 at 04:30:48PM +0200, Ulf Hansson wrote: > On Tue, 8 Jun 2021 at 16:23, Alan Stern wrote: > > > > On Tue, Jun 08, 2021 at 11:02:50AM +0200, Ulf Hansson wrote: > > > Recent changes to the PM core allows ->runtime_suspend|resume callbacks to > > > be unassigned. > > > > > > In the earlier behaviour the PM core would return -ENOSYS, when trying to > > > runtime resume a device, for example. Let's update the documentation to > > > clarify this. > > > > > > Signed-off-by: Ulf Hansson > > > --- > > > > > > Changes in v2: > > > - Added a new patch for the updating the docs, as pointed out by Alan. > > > > > > --- > > > Documentation/power/runtime_pm.rst | 8 ++++++++ > > > 1 file changed, 8 insertions(+) > > > > > > diff --git a/Documentation/power/runtime_pm.rst b/Documentation/power/runtime_pm.rst > > > index 18ae21bf7f92..3d09c9fd450d 100644 > > > --- a/Documentation/power/runtime_pm.rst > > > +++ b/Documentation/power/runtime_pm.rst > > > @@ -827,6 +827,14 @@ or driver about runtime power changes. Instead, the driver for the device's > > > parent must take responsibility for telling the device's driver when the > > > parent's power state changes. > > > > > > +Note that, in some cases it may not be desirable for subsystems/drivers to call More than 80 chars. > > > +pm_runtime_no_callbacks() for their devices. This could be because a subset of More than 80 chars. > > > +the runtime PM callbacks needs to be implemented, a platform dependent PM > > > +domain could get attached to the device or that the device is power manged s/manged/managed/ > > > +through a supplier device link. For these reasons and to avoid boilerplate code More than 80 chars. > > > +in subsystems/drivers, the PM core allows runtime PM callbacks to be > > > +unassigned. > > > + > > > > You should also mention that if a callback pointer is NULL, the > > runtime PM core will act as though there was a callback and it > > returned 0. That's an important consideration. > > Good point, let me add it. > > I send a new version of $subject patch, unless Rafael is happy to do > the amending when/if applying? > > > > > Also, notice that this file was carefully edited to make sure that > > none of the lines exceed 80 characters. Your new addition should > > be the same. > > Absolutely, but it should be okay already, no? See above. Alan