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From: Kai-Heng Feng <kai.heng.feng@canonical.com>
To: bhelgaas@google.com, rafael.j.wysocki@intel.com
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	Kai-Heng Feng <kai.heng.feng@canonical.com>,
	stable@vger.kernel.org
Subject: [PATCH v4] PCI / PM: Always check PME wakeup capability for runtime wakeup support
Date: Mon,  7 May 2018 14:11:20 +0800	[thread overview]
Message-ID: <20180507061120.3683-1-kai.heng.feng@canonical.com> (raw)

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 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")
Cc: stable@vger.kernel.org # 4.13+
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v4: Correct some errors in commit log.

v3: State the reason why the wakeup flag gets changed.

v2: Explicitly check dev->pme_support.

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

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index a04197ce767d..c2616cad3a1d 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2138,16 +2138,16 @@ bool pci_dev_run_wake(struct pci_dev *dev)
 {
 	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;
 
-- 
2.17.0

             reply	other threads:[~2018-05-07  6:11 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-07  6:11 Kai-Heng Feng [this message]
2018-05-07 21:48 ` Bjorn Helgaas
2018-05-08 22:14   ` Rafael J. Wysocki

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