Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754580AbcC1Rfs (ORCPT ); Mon, 28 Mar 2016 13:35:48 -0400 Received: from [198.137.202.9] ([198.137.202.9]:48596 "EHLO bombadil.infradead.org" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751212AbcC1Rfp (ORCPT ); Mon, 28 Mar 2016 13:35:45 -0400 Date: Mon, 28 Mar 2016 10:33:09 -0700 From: Darren Hart To: Gabriele Mazzotta , Rafael Wysocki Cc: Pali =?iso-8859-1?Q?Roh=E1r?= , "D. Jared Dominguez" , "platform-driver-x86@vger.kernel.org" , "Rafael J. Wysocki" , Alex Hung , Andrei Borzenkov , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended Message-ID: <20160328173309.GA26086@dvhart-mobl5.amr.corp.intel.com> References: <1457740175-8327-1-git-send-email-gabriele.mzt@gmail.com> <1458341063-8753-1-git-send-email-gabriele.mzt@gmail.com> <20160321121736.GH8413@pali> <20160324093915.GZ8413@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3028 Lines: 80 On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > 2016-03-24 10:39 GMT+01:00 Pali Roh?r : > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > >> 2016-03-21 13:17 GMT+01:00 Pali Roh?r : > >> > 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. Also, since there is no indication to the user that a failure occurs, this function is basically equivalent in the success and failure case (the success case is just slower). Am I missing something critical here? > > > -- > > Pali Roh?r > > pali.rohar@gmail.com > -- Darren Hart Intel Open Source Technology Center