[PATCH -v4 6/6] PCI,pciehp: identify device change during suspend

[Yijing Wang <wangyijing@huawei.com>]

If device was removed from slot and reinsert a new device during
suspend, pciehp can not identify the physical device change now.
So the old driver .resume() method will be called for the new device,
this is bad. If device support device serial number capability,
we can identify this by DSN. So the reasonable way is first remove
the old device, then enable the new device.

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Oliver Neukum <oneukum@suse.de>
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Cc: linux-pci@vger.kernel.org
---
 drivers/pci/hotplug/pciehp_core.c |   34 +++++++++++++++++++++++++++++++---
 1 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index 7fe9dbd..db5f597 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -301,6 +301,8 @@ static int pciehp_resume (struct pcie_device *dev)
 	struct controller *ctrl;
 	struct slot *slot;
 	struct pci_bus *pbus = dev->port->subordinate;
+	struct pci_dev *pdev;
+	int ret = 0;
 	u8 status;
 
 	ctrl = get_service_data(dev);
@@ -315,10 +317,36 @@ static int pciehp_resume (struct pcie_device *dev)
 	if (status) {
 		if (list_empty(&pbus->devices))
 			pciehp_enable_slot(slot);
-	} else if (!list_empty(&pbus->devices)) {
-		pciehp_disable_slot(slot);
+
+		pdev = pci_get_slot(pbus, PCI_DEVFN(0, 0));
+		if (!pdev)
+			return 0;
+		ret = pci_serial_number_changed(pdev);
+		pci_dev_put(pdev);
+		if (ret) {
+			/*
+			 * first power off slot, avoid the old driver
+			 * .remove() method touch the new hardware
+			 */
+			if (POWER_CTRL(ctrl)) {
+				ret = pciehp_power_off_slot(slot);
+				if (ret) {
+					ctrl_err(ctrl,
+						"Issue of Slot Disable command failed\n");
+					return 0;
+				}
+				msleep(1000);
+				pciehp_unconfigure_device(slot);
+				/* call child devices driver->suspend() for symmetry */
+				list_for_each_entry(pdev, &pbus->devices, bus_list)
+					if (pdev->driver)
+						pdev->driver->driver.pm->suspend(&pdev->dev);
+				pciehp_enable_slot(slot);
+			}
+		} else if (!list_empty(&pbus->devices)) {
+			pciehp_disable_slot(slot);
+		}
 	}
-	
 	return 0;
 }
 #endif /* PM */
-- 
1.7.1