linux-kernel - Re: [PATCH] PCI: PM: Skip devices in D0 for suspend-to-idle

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Message-ID: <20190613125718.GM2640@lahna.fi.intel.com>
Date:   Thu, 13 Jun 2019 15:57:18 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux PCI <linux-pci@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Keith Busch <kbusch@...nel.org>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>
Subject: Re: [PATCH] PCI: PM: Skip devices in D0 for suspend-to-idle

On Thu, Jun 13, 2019 at 12:14:02AM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Commit d491f2b75237 ("PCI: PM: Avoid possible suspend-to-idle issue")
> attempted to avoid a problem with devices whose drivers want them to
> stay in D0 over suspend-to-idle and resume, but it did not go as far
> as it should with that.
> 
> Namely, first of all, it is questionable to change the power state
> of a PCI bridge with a device in D0 under it, but that is not
> actively prevented from happening during system-wide PM transitions,
> so use the skip_bus_pm flag introduced by commit d491f2b75237 for
> that.
> 
> Second, the configuration of devices left in D0 (whatever the reason)
> during suspend-to-idle need not be changed and attempting to put them
> into D0 again by force may confuse some firmware, so explicitly avoid
> doing that.
> 
> Fixes: d491f2b75237 ("PCI: PM: Avoid possible suspend-to-idle issue")
> Reported-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>