Currently, pciehp_resume will call pciehp_enable_slot() to add
device if there is a device in the slot. But if the device was
present before suspend, it's no necessary to add again. Now in
such case, there is some uncomfortable message like
pciehp 0000:00:1c.1:pcie04: Device 0000:03:00.0 already exists at 0000:03:00, cannot hot-add
pciehp 0000:00:1c.1:pcie04: Cannot add device at 0000:03:00
This problem was reported by Paul Bolle <pebolle@xxxxxxxxxx>
The discussion link: http://comments.gmane.org/gmane.linux.kernel.pci/19876
We can use PCIe Device Serial Number to identify the device if
device support DSN.
currently:
1. slot is empty before suspend, insert card during suspend.
In this case, is safe, pciehp will add device by check adapter
status register in pciehp_resume.
2. slot is non empty before suspend, remove card during suspend.
Also be safe, pciehp will remove device by check adapter
status register in pciehp_resume.
3. slot is non empty before suspend, remove card during suspend
and insert a new card.
Now pciehp just call pciehp_enable_slot() roughly. We should
remove the old card firstly, then add the new card.
4. slot is non empty before suspend, no action during suspend.
We should do nothing in pciehp_resume, but we call
pciehp_enable_slot(), so some uncomfortable messages show like above.
In this case, we can improve it a little by add a guard
if (!list_empty(bus->devices)).
Reported-by: Paul Bolle <pebolle@xxxxxxxxxx>
Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
Cc: Paul Bolle <pebolle@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
Cc: Oliver Neukum <oneukum@xxxxxxx>
Cc: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx>
Cc: linux-pci@xxxxxxxxxxxxxxx
---
drivers/pci/hotplug/pciehp_core.c | 38 +++++++++++++++++++++++++++++++++---
1 files changed, 34 insertions(+), 4 deletions(-)
diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index 7d72c5e..d01e093 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -291,6 +291,28 @@ static void pciehp_remove(struct pcie_device *dev)
}
#ifdef CONFIG_PM
+
+/* If device support Device Serial Numner, use DSN
+ * to identify the device
+ */
+static bool device_in_slot_is_changed(struct pci_bus *pbus)
+{
+ u64 old_dsn, new_dsn;
+ struct pci_dev *pdev;
+
+ pdev = pci_get_slot(pbus, PCI_DEVFN(0, 0));
+ old_dsn = pdev->sn;
+
+ /* get func 0 device serial number */
+ pci_get_dsn(pdev, &new_dsn);
+ pci_dev_put(pdev);
+
+ if (old_dsn != new_dsn)
+ return true;
+
+ return false;
+}
+
static int pciehp_suspend (struct pcie_device *dev)
{
return 0;
@@ -300,6 +322,7 @@ static int pciehp_resume (struct pcie_device *dev)
{
struct controller *ctrl;
struct slot *slot;
+ struct pci_bus *pbus = dev->port->subordinate;
u8 status;
ctrl = get_service_data(dev);
@@ -311,10 +334,17 @@ static int pciehp_resume (struct pcie_device *dev)
/* Check if slot is occupied */
pciehp_get_adapter_status(slot, &status);
- if (status)
- pciehp_enable_slot(slot);
- else
- pciehp_disable_slot(slot);
+ if (status) {
+ if (list_empty(&pbus->devices))
+ pciehp_enable_slot(slot);
+ else if (device_in_slot_is_changed(pbus)) {
+ pciehp_disable_slot(slot);
+ pciehp_enable_slot(slot);
+ }
+ } else {
+ if (!list_empty(&pbus->devices))
+ pciehp_disable_slot(slot);
+ }
return 0;
}
#endif /* PM */
--
1.7.1
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