linux-kernel - [ 106/123] PCI/PM: Do not suspend port if any subordinate device needs PME polling

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Message-Id: <20130109201512.087668690@linuxfoundation.org>
Date:	Wed,  9 Jan 2013 12:35:45 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk, Ulrich Eckhardt <usb@...-eckhardt.de>,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	Huang Ying <ying.huang@...el.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [ 106/123] PCI/PM: Do not suspend port if any subordinate device needs PME polling

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

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

From: Huang Ying <ying.huang@...el.com>

commit c733b77475707cc3980542c86ee0ad5c841d544c upstream.

Ulrich reported that his USB3 cardreader does not work reliably when
connected to the USB3 port.  It turns out that USB3 controller failed to
awaken when plugging in the USB3 cardreader.  Further experiments found
that the USB3 host controller can only be awakened via polling, not via PME
interrupt.  But if the PCIe port to which the USB3 host controller is
connected is suspended, we cannot poll the controller because its config
space is not accessible when the PCIe port is in a low power state.

To solve the issue, the PCIe port will not be suspended if any subordinate
device needs PME polling.

[bhelgaas: use bool consistently rather than mixing int/bool]
Reference: http://lkml.kernel.org/r/50841CCC.9030809@uli-eckhardt.de
Reported-by: Ulrich Eckhardt <usb@...-eckhardt.de>
Tested-by: Sarah Sharp <sarah.a.sharp@...ux.intel.com>
Signed-off-by: Huang Ying <ying.huang@...el.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/pci/pcie/portdrv_pci.c |   20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/drivers/pci/pcie/portdrv_pci.c
@@ -134,10 +134,28 @@ static int pcie_port_runtime_resume(stru
 	return 0;
 }

+static int pci_dev_pme_poll(struct pci_dev *pdev, void *data)
+{
+	bool *pme_poll = data;
+
+	if (pdev->pme_poll)
+		*pme_poll = true;
+	return 0;
+}
+
 static int pcie_port_runtime_idle(struct device *dev)
 {
+	struct pci_dev *pdev = to_pci_dev(dev);
+	bool pme_poll = false;
+
+	/*
+	 * If any subordinate device needs pme poll, we should keep
+	 * the port in D0, because we need port in D0 to poll it.
+	 */
+	pci_walk_bus(pdev->subordinate, pci_dev_pme_poll, &pme_poll);
 	/* Delay for a short while to prevent too frequent suspend/resume */
-	pm_schedule_suspend(dev, 10);
+	if (!pme_poll)
+		pm_schedule_suspend(dev, 10);
 	return -EBUSY;
 }
 #else

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