linux-kernel - [PATCH 4.14 44/62] PCI / PM: Always check PME wakeup capability for runtime wakeup support

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Date:   Mon, 14 May 2018 08:49:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 4.14 44/62] PCI / PM: Always check PME wakeup capability for runtime wakeup support

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kai Heng Feng <kai.heng.feng@...onical.com>

commit 8feaec33b9868582654cd3d5355225dcb79aeca6 upstream.

USB controller ASM1042 stops working after commit de3ef1eb1cd0 (PM /
core: Drop run_wake flag from struct dev_pm_info).

The device in question is not power managed by platform firmware,
furthermore, it only supports PME# from D3cold:
Capabilities: [78] Power Management version 3
       Flags: PMEClk- DSI- D1- D2- AuxCurrent=55mA PME(D0-,D1-,D2-,D3hot-,D3cold+)
       Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-

Before commit de3ef1eb1cd0, the device never gets runtime suspended.
After that commit, the device gets runtime suspended to D3hot, which can
not generate any PME#.

usb_hcd_pci_probe() unconditionally calls device_wakeup_enable(), hence
device_can_wakeup() in pci_dev_run_wake() always returns true.

So pci_dev_run_wake() needs to check PME wakeup capability as its first
condition.

In addition, change wakeup flag passed to pci_target_state() from false
to true, because we want to find the deepest state different from D3cold
that the device can still generate PME#. In this case, it's D0 for the
device in question.

Fixes: de3ef1eb1cd0 (PM / core: Drop run_wake flag from struct dev_pm_info)
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc: 4.13+ <stable@...r.kernel.org> # 4.13+
Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/pci/pci.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2120,16 +2120,16 @@ bool pci_dev_run_wake(struct pci_dev *de
 {
 	struct pci_bus *bus = dev->bus;

-	if (device_can_wakeup(&dev->dev))
-		return true;
-
 	if (!dev->pme_support)
 		return false;

 	/* PME-capable in principle, but not from the target power state */
-	if (!pci_pme_capable(dev, pci_target_state(dev, false)))
+	if (!pci_pme_capable(dev, pci_target_state(dev, true)))
 		return false;

+	if (device_can_wakeup(&dev->dev))
+		return true;
+
 	while (bus->parent) {
 		struct pci_dev *bridge = bus->self;