Patch "drivers/pci/hotplug: Fix initial state for empty slot" has been added to the 4.9-stable tree

Patch "drivers/pci/hotplug: Fix initial state for empty slot" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drivers-pci-hotplug-fix-initial-state-for-empty-slot.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From d0c424971f70501ec0a0364117b9934db039c9cc Mon Sep 17 00:00:00 2001
From: Gavin Shan <gwshan@linux.vnet.ibm.com>
Date: Wed, 11 Jan 2017 11:50:07 +1100
Subject: drivers/pci/hotplug: Fix initial state for empty slot

From: Gavin Shan <gwshan@linux.vnet.ibm.com>

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>

---
 drivers/pci/hotplug/pnv_php.c |   16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

--- 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
 	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


Patches currently in stable-queue which might be from gwshan@linux.vnet.ibm.com are

queue-4.9/pci-hotplug-pnv-php-remove-warn_on-in-pnv_php_put_slot.patch
queue-4.9/pci-hotplug-pnv-php-disable-surprise-hotplug-capability-on-conflicts.patch
queue-4.9/drivers-pci-hotplug-handle-presence-detection-change-properly.patch
queue-4.9/drivers-pci-hotplug-fix-initial-state-for-empty-slot.patch