PCI: pciehp: Acknowledge spurious "cmd completed" event

In case of a spurious "cmd completed", pcie_write_cmd() does not clear it,
but yet expects more "cmd completed" events to be generated.  This does not
happen because the previous (spurious) event has not been acknowledged.
Fix that.
Signed-off-by: NRajat Jain <rajatxjain@gmail.com>
Signed-off-by: NRajat Jain <rajatjain@juniper.net>
Signed-off-by: NGuenter Roeck <groeck@juniper.net>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/pci/hotplug/pciehp_hpc.c

@@ -159,6 +159,8 @@ static void pcie_write_cmd(struct controller *ctrl, u16 cmd, u16 mask)
 
 	pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
 	if (slot_status & PCI_EXP_SLTSTA_CC) {
+		pcie_capability_write_word(pdev, PCI_EXP_SLTSTA,
+					   PCI_EXP_SLTSTA_CC);
 		if (!ctrl->no_cmd_complete) {
 			/*
 			 * After 1 sec and CMD_COMPLETED still not set, just