From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Darren Hart <dvhart@infradead.org>
Cc: "Gabriele Mazzotta" <gabriele.mzt@gmail.com>,
"Pali Rohár" <pali.rohar@gmail.com>,
"D. Jared Dominguez" <Jared_Dominguez@dell.com>,
"platform-driver-x86@vger.kernel.org"
<platform-driver-x86@vger.kernel.org>,
"Alex Hung" <alex.hung@canonical.com>,
"Andrei Borzenkov" <arvidjaar@gmail.com>,
"linux-kernel@vger.kernel.org" <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 [thread overview]
Message-ID: <4072492.lANJWhSkYa@vostro.rjw.lan> (raw)
In-Reply-To: <20160328173309.GA26086@dvhart-mobl5.amr.corp.intel.com>
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 <pali.rohar@gmail.com>:
> > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>:
> > >> > 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
next prev parent reply other threads:[~2016-03-29 13:09 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-11 23:49 [PATCH v2] dell-rbtn: Ignore ACPI notifications if device is suspended Gabriele Mazzotta
2016-03-14 7:55 ` Alex Hung
2016-03-14 11:34 ` Gabriele Mazzotta
2016-03-14 11:45 ` Pali Rohár
2016-03-14 12:15 ` Andrei Borzenkov
2016-03-18 15:57 ` Andrei Borzenkov
2016-04-18 12:31 ` Pali Rohár
2016-03-18 22:44 ` [PATCH v3] " Gabriele Mazzotta
2016-03-21 12:17 ` Pali Rohár
2016-03-21 15:13 ` Gabriele Mazzotta
2016-03-24 9:39 ` Pali Rohár
2016-03-24 11:24 ` Gabriele Mazzotta
2016-03-28 17:33 ` Darren Hart
2016-03-28 17:58 ` Gabriele Mazzotta
2016-03-28 18:56 ` Darren Hart
2016-03-28 19:41 ` Gabriele Mazzotta
2016-03-29 5:24 ` Darren Hart
2016-03-29 11:13 ` Gabriele Mazzotta
2016-03-29 13:11 ` Rafael J. Wysocki [this message]
2016-04-18 12:35 ` Pali Rohár
2016-04-25 20:06 ` Gabriele Mazzotta
2016-05-19 13:30 ` Pali Rohár
2016-05-19 20:18 ` Darren Hart
2016-05-23 21:26 ` Darren Hart
2016-05-23 22:06 ` Pali Rohár
2016-05-23 22:17 ` Darren Hart
2016-05-23 22:22 ` Pali Rohár
2016-05-23 23:03 ` Gabriele Mazzotta
2016-05-24 3:48 ` Andrei Borzenkov
2016-05-24 7:09 ` Pali Rohár
2016-05-24 19:57 ` Darren Hart
2016-05-24 20:53 ` [PATCH v4] " Gabriele Mazzotta
2016-05-25 20:28 ` Darren Hart
2016-05-25 20:36 ` Pali Rohár
2016-05-25 20:47 ` Gabriele Mazzotta
2016-05-25 21:20 ` Darren Hart
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