PCI: pciehp: Track enable/disable status

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>

1 files changed, 16 insertions, 12 deletions

diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index a4a8a5457aca..627e846df802 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -147,13 +147,12 @@ void pciehp_queue_pushbutton_work(struct work_struct *work)
 void pciehp_handle_button_press(struct slot *p_slot)
 {
 	struct controller *ctrl = p_slot->ctrl;
-	u8 getstatus;
 
 	mutex_lock(&p_slot->lock);
 	switch (p_slot->state) {
-	case STATIC_STATE:
-		pciehp_get_power_status(p_slot, &getstatus);
-		if (getstatus) {
+	case OFF_STATE:
+	case ON_STATE:
+		if (p_slot->state == ON_STATE) {
 			p_slot->state = BLINKINGOFF_STATE;
 			ctrl_info(ctrl, "Slot(%s): Powering off due to button press\n",
 				  slot_name(p_slot));
@@ -176,14 +175,16 @@ void pciehp_handle_button_press(struct slot *p_slot)
 		 */
 		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));
-		p_slot->state = STATIC_STATE;
 		break;
 	case POWEROFF_STATE:
 	case POWERON_STATE:
@@ -216,7 +217,8 @@ void pciehp_handle_link_change(struct slot *p_slot)
 	case BLINKINGOFF_STATE:
 		cancel_delayed_work(&p_slot->work);
 		/* Fall through */
-	case STATIC_STATE:
+	case ON_STATE:
+	case OFF_STATE:
 		if (link_active) {
 			p_slot->state = POWERON_STATE;
 			mutex_unlock(&p_slot->lock);
@@ -332,7 +334,7 @@ int pciehp_enable_slot(struct slot *slot)
 		pciehp_green_led_off(slot); /* may be blinking */
 
 	mutex_lock(&slot->lock);
-	slot->state = STATIC_STATE;
+	slot->state = ret ? OFF_STATE : ON_STATE;
 	mutex_unlock(&slot->lock);
 
 	return ret;
@@ -368,7 +370,7 @@ int pciehp_disable_slot(struct slot *slot)
 	mutex_unlock(&slot->hotplug_lock);
 
 	mutex_lock(&slot->lock);
-	slot->state = STATIC_STATE;
+	slot->state = OFF_STATE;
 	mutex_unlock(&slot->lock);
 
 	return ret;
@@ -382,7 +384,7 @@ int pciehp_sysfs_enable_slot(struct slot *p_slot)
 	switch (p_slot->state) {
 	case BLINKINGON_STATE:
 		cancel_delayed_work(&p_slot->work);
-	case STATIC_STATE:
+	case OFF_STATE:
 		p_slot->state = POWERON_STATE;
 		mutex_unlock(&p_slot->lock);
 		return pciehp_enable_slot(p_slot);
@@ -391,6 +393,7 @@ int pciehp_sysfs_enable_slot(struct slot *p_slot)
 			  slot_name(p_slot));
 		break;
 	case BLINKINGOFF_STATE:
+	case ON_STATE:
 	case POWEROFF_STATE:
 		ctrl_info(ctrl, "Slot(%s): Already enabled\n",
 			  slot_name(p_slot));
@@ -413,7 +416,7 @@ int pciehp_sysfs_disable_slot(struct slot *p_slot)
 	switch (p_slot->state) {
 	case BLINKINGOFF_STATE:
 		cancel_delayed_work(&p_slot->work);
-	case STATIC_STATE:
+	case ON_STATE:
 		p_slot->state = POWEROFF_STATE;
 		mutex_unlock(&p_slot->lock);
 		return pciehp_disable_slot(p_slot);
@@ -422,6 +425,7 @@ int pciehp_sysfs_disable_slot(struct slot *p_slot)
 			  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));