drivers/pci/hotplug: Fix initial state for empty slot

BugLink: http://bugs.launchpad.net/bugs/1673118
commit d0c424971f70501ec0a0364117b9934db039c9cc upstream.

In PowerNV PCI hotplug driver, the initial PCI slot's state is set
to PNV_PHP_STATE_POPULATED if no PCI devices are connected to the
slot. The PCI devices that are hot added to the slot won't be probed
and populated because of the check in pnv_php_enable():

        /* Check if the slot has been configured */
        if (php_slot->state != PNV_PHP_STATE_REGISTERED)
                return 0;

This fixes the issue by leaving the slot in PNV_PHP_STATE_REGISTERED
state initially if nothing is connected to the slot.

Fixes: 360aebd85a4 ("drivers/pci/hotplug: Support surprise hotplug in powernv driver")
Reported-by: Hank Chang <hankmax0000@gmail.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Tested-by: Willie Liauw <williel@supermicro.com.tw>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
index e1c29909e7d3e8d391310e729940eb9c09460afe..e96973b95e7ac4c0b26a8a7e0e1bd4ed3ce1deab 100644 (file)
--- a/drivers/pci/hotplug/pnv_php.c
+++ b/drivers/pci/hotplug/pnv_php.c
@@ -436,9 +436,21 @@ static int pnv_php_enable(struct pnv_php_slot *php_slot, bool rescan)
        if (ret)
                return ret;
 
-       /* Proceed if there have nothing behind the slot */
-       if (presence == OPAL_PCI_SLOT_EMPTY)
+       /*
+        * Proceed if there have nothing behind the slot. However,
+        * we should leave the slot in registered state at the
+        * beginning. Otherwise, the PCI devices inserted afterwards
+        * won't be probed and populated.
+        */
+       if (presence == OPAL_PCI_SLOT_EMPTY) {
+               if (!php_slot->power_state_check) {
+                       php_slot->power_state_check = true;
+
+                       return 0;
+               }
+
                goto scan;
+       }
 
        /*
         * If the power supply to the slot is off, we can't detect