From 9590192f2584c2cfc2fee88be22fe6e8921ed115 Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@wunner.de>
Date: Thu, 19 Jul 2018 17:27:45 -0500
Subject: [PATCH] PCI: pciehp: Track enable/disable status
Git-commit: 9590192f2584c2cfc2fee88be22fe6e8921ed115
Patch-mainline: v4.19
References: FATE#326303

handle_button_press_event() currently determines whether the slot has
been turned on or off by looking at the Power Controller Control bit in
the Slot Control register.  This assumes that an attention button
implies presence of a power controller even though that's not mandated
by the spec.  Moreover the Power Controller Control bit is unreliable
when a power fault occurs (PCIe r4.0, sec 6.7.1.8).  This issue has
existed since the driver was introduced in 2004.

Fix by replacing STATIC_STATE with ON_STATE and OFF_STATE and tracking
whether the slot has been turned on or off.  This is also a required
ingredient to make pciehp resilient to missed events, which is the
object of an upcoming commit.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/pci/hotplug/pciehp.h      |   15 ++++++++++++++-
 drivers/pci/hotplug/pciehp_ctrl.c |    8 ++++++--
 drivers/pci/hotplug/pciehp_hpc.c  |    5 +++++
 3 files changed, 25 insertions(+), 3 deletions(-)

--- a/drivers/pci/hotplug/pciehp.h
+++ b/drivers/pci/hotplug/pciehp.h
@@ -97,11 +97,24 @@ struct controller {
 	atomic_t pending_events;
 };
 
-#define STATIC_STATE			0
+/**
+ * DOC: Slot state
+ *
+ * @OFF_STATE: slot is powered off, no subordinate devices are enumerated
+ * @BLINKINGON_STATE: slot will be powered on after the 5 second delay,
+ *	green led is blinking
+ * @BLINKINGOFF_STATE: slot will be powered off after the 5 second delay,
+ *	green led is blinking
+ * @POWERON_STATE: slot is currently powering on
+ * @POWEROFF_STATE: slot is currently powering off
+ * @ON_STATE: slot is powered on, subordinate devices have been enumerated
+ */
+#define OFF_STATE			0
 #define BLINKINGON_STATE		1
 #define BLINKINGOFF_STATE		2
 #define POWERON_STATE			3
 #define POWEROFF_STATE			4
+#define ON_STATE			5
 
 #define ATTN_BUTTN(ctrl)	((ctrl)->slot_cap & PCI_EXP_SLTCAP_ABP)
 #define POWER_CTRL(ctrl)	((ctrl)->slot_cap & PCI_EXP_SLTCAP_PCP)
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -195,10 +195,13 @@ void pciehp_handle_button_press(struct s
 		 */
 		ctrl_info(ctrl, "Slot(%s): Button cancel\n", slot_name(p_slot));
 		cancel_delayed_work(&p_slot->work);
-		if (p_slot->state == BLINKINGOFF_STATE)
+		if (p_slot->state == BLINKINGOFF_STATE) {
+			p_slot->state = ON_STATE;
 			pciehp_green_led_on(p_slot);
-		else
+		} else {
+			p_slot->state = OFF_STATE;
 			pciehp_green_led_off(p_slot);
+		}
 		pciehp_set_attention_status(p_slot, 0);
 		ctrl_info(ctrl, "Slot(%s): Action canceled due to button press\n",
 			  slot_name(p_slot));
@@ -443,6 +446,7 @@ int pciehp_sysfs_disable_slot(struct slo
 			  slot_name(p_slot));
 		break;
 	case BLINKINGON_STATE:
+	case OFF_STATE:
 	case POWERON_STATE:
 		ctrl_info(ctrl, "Slot(%s): Already disabled\n",
 			  slot_name(p_slot));
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -777,6 +777,7 @@ void pcie_shutdown_notification(struct c
 
 static int pcie_init_slot(struct controller *ctrl)
 {
+	struct pci_bus *subordinate = ctrl_dev(ctrl)->subordinate;
 	struct slot *slot;
 
 	slot = kzalloc(sizeof(*slot), GFP_KERNEL);
@@ -787,6 +788,10 @@ static int pcie_init_slot(struct control
 	if (!slot->wq)
 		goto abort;
 
+	down_read(&pci_bus_sem);
+	slot->state = list_empty(&subordinate->devices) ? OFF_STATE : ON_STATE;
+	up_read(&pci_bus_sem);
+
 	slot->ctrl = ctrl;
 	mutex_init(&slot->lock);
 	mutex_init(&slot->hotplug_lock);