Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756137AbcC2NJS (ORCPT ); Tue, 29 Mar 2016 09:09:18 -0400 Received: from cloudserver094114.home.net.pl ([79.96.170.134]:51467 "HELO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751525AbcC2NJP convert rfc822-to-8bit (ORCPT ); Tue, 29 Mar 2016 09:09:15 -0400 From: "Rafael J. Wysocki" To: Darren Hart Cc: Gabriele Mazzotta , Pali =?ISO-8859-1?Q?Roh=E1r?= , "D. Jared Dominguez" , "platform-driver-x86@vger.kernel.org" , Alex Hung , Andrei Borzenkov , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended Date: Tue, 29 Mar 2016 15:11:35 +0200 Message-ID: <4072492.lANJWhSkYa@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.5.0-rc1+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <20160328173309.GA26086@dvhart-mobl5.amr.corp.intel.com> References: <1457740175-8327-1-git-send-email-gabriele.mzt@gmail.com> <20160328173309.GA26086@dvhart-mobl5.amr.corp.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3072 Lines: 71 On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote: > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > > 2016-03-24 10:39 GMT+01:00 Pali Rohár : > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár : > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > > >> >> +#ifdef CONFIG_PM_SLEEP > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > > >> >> +{ > > >> >> + struct rbtn_data *rbtn_data = context; > > >> >> + > > >> >> + rbtn_data->suspended = false; > > >> >> +} > > >> >> + > > >> >> +static int rbtn_suspend(struct device *dev) > > >> >> +{ > > >> >> + struct acpi_device *device = to_acpi_device(dev); > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > >> >> + > > >> >> + rbtn_data->suspended = true; > > >> >> + > > >> >> + return 0; > > >> >> +} > > >> >> + > > >> >> +static int rbtn_resume(struct device *dev) > > >> >> +{ > > >> >> + struct acpi_device *device = to_acpi_device(dev); > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > >> >> + acpi_status status; > > >> >> + > > >> >> + /* > > >> >> + * Clear the flag only after we received the extra > > >> >> + * ACPI notification. > > >> >> + */ > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > > >> >> + rbtn_acpi_clear_flag, rbtn_data); > > >> >> + if (ACPI_FAILURE(status)) > > >> >> + rbtn_data->suspended = false; > > >> > > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > > >> > right? And that will set suspended to false. When acpi_os_execute fails, > > >> > then it set suspended too to false... Then whole acpi_os_execute doing > > >> > just "barrier" after which suspended flag can be set to false. So I > > >> > think rbtn_acpi_clear_flag function is not needed here. > > >> > > > >> > Cannot you pass NULL or empty function pointer as callback? Or what was > > >> > reason to do that flag clearing at "two places"? > > >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so > > >> I can't clear the flag from rbtn_resume. > > > > > > acpi_os_execute calls callback asynchronously later? Or what exactly do it? > > > > In this case, it adds the callback to the kacpi_notify_wq workqueue > > for deferred execution. > > +Rafael for context/advice on the use of acpi_os_execute here. > > This is true, but a quick scan through that call path doesn't tell me why we > would need to call it here instead of just setting rbtn_data->suspended = false. > The comment suggests waiting for the event, but is that what this is doing? It > appears to me to be immediately scheduling the function to a work queue, not > waiting for the event notifier. I think this is supposed to work as a barrier. That is, it will only run after all events in the queue have been processed. I'm not sure if that's necessary, though. Thanks, Rafael