Revert "PCI: pciehp: Add runtime PM support for PCIe hotplug ports"

This reverts commit 68db9bc814362e7f24371c27d12a4f34477d9356.

Yinghai reported that the following manual hotplug sequence:

# echo 0 > /sys/bus/pci/slots/8/power
# echo 1 > /sys/bus/pci/slots/8/power

worked in v4.9, but fails in v4.10-rc1, and that reverting 68db9bc81436
("PCI: pciehp: Add runtime PM support for PCIe hotplug ports") makes it
work again.

Fixes: 68db9bc81436 ("PCI: pciehp: Add runtime PM support for PCIe hotplug ports")
Link: https://lkml.kernel.org/r/CAE9FiQVCMCa7iVyuwp9z6VrY0cE7V_xghuXip28Ft52=[e-mail]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=193951
Reported-by: Yinghai Lu <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>

drivers/pci/hotplug/pciehp_ctrl.c

···
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/slab.h>
-#include <linux/pm_runtime.h>
 #include <linux/pci.h>
 #include "../pci.h"
 #include "pciehp.h"
···
 	pciehp_green_led_blink(p_slot);
 
 	/* Check link training status */
-	pm_runtime_get_sync(&ctrl->pcie->port->dev);
 	retval = pciehp_check_link_status(ctrl);
 	if (retval) {
 		ctrl_err(ctrl, "Failed to check link status\n");
···
 		if (retval != -EEXIST)
 			goto err_exit;
 	}
-	pm_runtime_put(&ctrl->pcie->port->dev);
 
 	pciehp_green_led_on(p_slot);
 	pciehp_set_attention_status(p_slot, 0);
 	return 0;
 
 err_exit:
-	pm_runtime_put(&ctrl->pcie->port->dev);
 	set_slot_off(ctrl, p_slot);
 	return retval;
 }
···
 	int retval;
 	struct controller *ctrl = p_slot->ctrl;
 
-	pm_runtime_get_sync(&ctrl->pcie->port->dev);
 	retval = pciehp_unconfigure_device(p_slot);
-	pm_runtime_put(&ctrl->pcie->port->dev);
 	if (retval)
 		return retval;
 

drivers/pci/pci.c

···
 			return false;
 
 		/*
-		 * Hotplug ports handled by firmware in System Management Mode
+		 * Hotplug interrupts cannot be delivered if the link is down,
+		 * so parents of a hotplug port must stay awake. In addition,
+		 * hotplug ports handled by firmware in System Management Mode
 		 * may not be put into D3 by the OS (Thunderbolt on non-Macs).
+		 * For simplicity, disallow in general for now.
 		 */
-		if (bridge->is_hotplug_bridge && !pciehp_is_native(bridge))
+		if (bridge->is_hotplug_bridge)
 			return false;
 
 		if (pci_bridge_d3_force)
···
 	     !pci_pme_capable(dev, PCI_D3cold)) ||
 
 	    /* If it is a bridge it must be allowed to go to D3. */
-	    !pci_power_manageable(dev) ||
-
-	    /* Hotplug interrupts cannot be delivered if the link is down. */
-	    dev->is_hotplug_bridge)
+	    !pci_power_manageable(dev))
 
 		*d3cold_ok = false;