PCI: pciehp: Enable link state change notifications

Enable the Link state notifications unconditionally. Enable the
presence detection notification only if attention button is absent.
This was discussed at this thread:
    https://lkml.kernel.org/r/529E5C0E.80903@gmail.com

Signed-off-by: Rajat Jain <rajatxjain@gmail.com>
Signed-off-by: Rajat Jain <rajatjain@juniper.net>
Signed-off-by: Guenter Roeck <groeck@juniper.net>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index b413dce8f194..245a3cb5d2f3 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -600,9 +600,17 @@ void pcie_enable_notification(struct controller *ctrl)
          * when it is cleared in the interrupt service routine, and
          * next power fault detected interrupt was notified again.
          */
-        cmd = PCI_EXP_SLTCTL_PDCE;
+
+        /*
+         * Always enable link events: thus link-up and link-down shall
+         * always be treated as hotplug and unplug respectively. Enable
+         * presence detect only if Attention Button is not present.
+         */
+        cmd = PCI_EXP_SLTCTL_DLLSCE;
         if (ATTN_BUTTN(ctrl))
                 cmd |= PCI_EXP_SLTCTL_ABPE;
+        else
+                cmd |= PCI_EXP_SLTCTL_PDCE;
         if (MRL_SENS(ctrl))
                 cmd |= PCI_EXP_SLTCTL_MRLSCE;
         if (!pciehp_poll_mode)
@@ -610,7 +618,8 @@ void pcie_enable_notification(struct controller *ctrl)
 
         mask = (PCI_EXP_SLTCTL_PDCE | PCI_EXP_SLTCTL_ABPE |
                 PCI_EXP_SLTCTL_MRLSCE | PCI_EXP_SLTCTL_PFDE |
-                PCI_EXP_SLTCTL_HPIE | PCI_EXP_SLTCTL_CCIE);
+                PCI_EXP_SLTCTL_HPIE | PCI_EXP_SLTCTL_CCIE |
+                PCI_EXP_SLTCTL_DLLSCE);
 
         pcie_write_cmd(ctrl, cmd, mask);
 }