linux-kernel - Re: [PATCH] PCI: PM: Avoid skipping bus-level PM on platforms without ACPI

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Message-ID: <CAJZ5v0gAejzYYo1TO01K3xTfZDr-1UT6XsVxY=u4LvnHmNcc9w@mail.gmail.com>
Date:   Wed, 26 Jun 2019 23:52:54 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PCI <linux-pci@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Jon Hunter <jonathanh@...dia.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>
Subject: Re: [PATCH] PCI: PM: Avoid skipping bus-level PM on platforms without ACPI

On Wed, Jun 26, 2019 at 2:56 PM Mika Westerberg
<mika.westerberg@...ux.intel.com> wrote:
>
> On Wed, Jun 26, 2019 at 12:20:23AM +0200, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > There are platforms that do not call pm_set_suspend_via_firmware(),
> > so pm_suspend_via_firmware() returns 'false' on them, but the power
> > states of PCI devices (PCIe ports in particular) are changed as a
> > result of powering down core platform components during system-wide
> > suspend.  Thus the pm_suspend_via_firmware() checks in
> > pci_pm_suspend_noirq() and pci_pm_resume_noirq() introduced by
> > commit 3e26c5feed2a ("PCI: PM: Skip devices in D0 for suspend-to-
> > idle") are not sufficient to determine that devices left in D0
> > during suspend will remain in D0 during resume and so the bus-level
> > power management can be skipped for them.
> >
> > For this reason, introduce a new global suspend flag,
> > PM_SUSPEND_FLAG_NO_PLATFORM, set it for suspend-to-idle only
> > and replace the pm_suspend_via_firmware() checks mentioned above
> > with checks against this flag.
> >
> > Fixes: 3e26c5feed2a ("PCI: PM: Skip devices in D0 for suspend-to-idle")
> > Reported-by: Jon Hunter <jonathanh@...dia.com>
> > Tested-by: Jon Hunter <jonathanh@...dia.com>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> I tested this patch on top of your (and mine) previous patches touching
> the ACPI/PCI PM and did not see any issues over several suspend-to-idle
> cycles with and without TBT device connected.
>
> Tested-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>

Thanks!