linux-kernel - Fwd: [PATCH] PM / Driver core: leave runtime PM enabled during system shutdown

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Message-ID: <CABoJqzySAVcraWOB_ebj2bOcm0M3MfiACzspcXpQyOEUmU8KhQ@mail.gmail.com>
Date:	Thu, 1 Mar 2012 18:30:36 +0200
From:	"Shlyakhovoy, Kostyantyn" <x0155534@...com>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...e.de>
Subject: Fwd: [PATCH] PM / Driver core: leave runtime PM enabled during system shutdown

> From fe6b91f47080eb17d21cbf2a39311877d57f6938 Mon Sep 17 00:00:00 2001
> From: Alan Stern <stern@...land.harvard.edu>
> Date: Tue, 6 Dec 2011 23:24:52 +0100
> Subject: [PATCH] PM / Driver core: leave runtime PM enabled during system
>  shutdown
>
> Disabling all runtime PM during system shutdown turns out not to be a
> good idea, because some devices may need to be woken up from a
> low-power state at that time.
>
> The whole point of disabling runtime PM for system shutdown was to
> prevent untimely runtime-suspend method calls.  This patch (as1504)
> accomplishes the same result by incrementing the usage count for each
> device and waiting for ongoing runtime-PM callbacks to finish.  This
> is what we already do during system suspend and hibernation, which
> makes sense since the shutdown method is pretty much a legacy analog
> of the pm->poweroff method.
>
> This fixes a recent regression on some OMAP systems introduced by
> commit af8db1508f2c9f3b6e633e2d2d906c6557c617f9 (PM / driver core:
> disable device's runtime PM during shutdown).
>
> Reported-and-tested-by: NeilBrown <neilb@...e.de>
> Signed-off-by: Alan Stern <stern@...land.harvard.edu>
> Acked-by: Greg Kroah-Hartman <gregkh@...e.de>
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> ---
>  drivers/base/core.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index d8b3d89..919daa7 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1743,8 +1743,10 @@ void device_shutdown(void)
>                 */
>                list_del_init(&dev->kobj.entry);
>                spin_unlock(&devices_kset->list_lock);
> -               /* Disable all device's runtime power management */
> -               pm_runtime_disable(dev);
> +
> +               /* Don't allow any more runtime suspends */
> +               pm_runtime_get_noresume(dev);
> +               pm_runtime_barrier(dev);
>
>                if (dev->bus && dev->bus->shutdown) {
>                        dev_dbg(dev, "shutdown\n");
> --
> 1.7.6.5

Hi Greg,

This patch exists in linux-3.2.y branch and fixes a regression
introduced by commit af8db1508f2c9f3b6e633e2d2d906c6557c617f9 - PM /
driver core: disable device's runtime PM during shutdown. However the
regression was introduced in linux-3.0.y and linux-3.1.y also.
Could you, please, merge this fix to linux-3.0.y and linux-3.1.y as well?

Regards,
Konstantin
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