linux-kernel - [PATCH 3.2 009/199] PCI: Check for PME in targeted sleep state

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Date:   Fri, 10 Mar 2017 11:46:10 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Lukas Wunner" <lukas@...ner.de>,
        "Alan Stern" <stern@...land.harvard.edu>,
        "Bjorn Helgaas" <bhelgaas@...gle.com>,
        "Pierre de Villemereuil" <flyos@...loo.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 3.2 009/199] PCI: Check for PME in targeted sleep state

3.2.87-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Alan Stern <stern@...land.harvard.edu>

commit 6496ebd7edf446fccf8266a1a70ffcb64252593e upstream.

One some systems, the firmware does not allow certain PCI devices to be put
in deep D-states.  This can cause problems for wakeup signalling, if the
device does not support PME# in the deepest allowed suspend state.  For
example, Pierre reports that on his system, ACPI does not permit his xHCI
host controller to go into D3 during runtime suspend -- but D3 is the only
state in which the controller can generate PME# signals.  As a result, the
controller goes into runtime suspend but never wakes up, so it doesn't work
properly.  USB devices plugged into the controller are never detected.

If the device relies on PME# for wakeup signals but is not capable of
generating PME# in the target state, the PCI core should accurately report
that it cannot do wakeup from runtime suspend.  This patch modifies the
pci_dev_run_wake() routine to add this check.

Reported-by: Pierre de Villemereuil <flyos@...loo.org>
Tested-by: Pierre de Villemereuil <flyos@...loo.org>
Signed-off-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
CC: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/pci/pci.c | 4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1763,6 +1763,10 @@ bool pci_dev_run_wake(struct pci_dev *de
 	if (!dev->pme_support)
 		return false;

+	/* PME-capable in principle, but not from the intended sleep state */
+	if (!pci_pme_capable(dev, pci_target_state(dev)))
+		return false;
+
 	while (bus->parent) {
 		struct pci_dev *bridge = bus->self;