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

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Date:   Wed, 26 Jun 2019 15:56:05 +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>,
        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 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>