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Commit e705c295 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Bjorn Helgaas
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PCI: pciehp: Drop pointless ACPI-based "slot detection" check 

Jarod Wilson reports that ExpressCard hotplug doesn't work on HP ZBook G2.
The problem turns out to be the ACPI-based "slot detection" code called
from pciehp_probe() which uses questionable heuristics based on what ACPI
objects are present for the PCIe port device to figure out whether to
register a hotplug slot for that port.

That code is used if there is at least one PCIe port having an ACPI device
configuration object related to hotplug (such as _EJ0 or _RMV), and the
Thunderbolt port on the ZBook has _RMV.  Of course, Thunderbolt and PCIe
native hotplug need not be mutually exclusive (as they aren't on the
ZBook), so that rule is simply incorrect.

Moreover, the ACPI-based "slot detection" check does not add any value if
pciehp_probe() is called at all and the service type of the device object
it has been called for is PCIE_PORT_SERVICE_HP, because PCIe hotplug
services are only registered if the _OSC handshake in acpi_pci_root_add()
allows the kernel to control the PCIe native hotplug feature.  No more
checks need to be carried out to decide whether or not to register a native
PCIe hotlug slot in that case.

For the above reasons, make pciehp_probe() check if it has been called for
the right service type and drop the pointless ACPI-based "slot detection"
check from it.  Also remove the entire code whose only user is that check
(the entire pciehp_acpi.c file goes away as a result) and drop function
headers related to it from the internal pciehp header file.

Link: http://lkml.kernel.org/r/1431632038-39917-1-git-send-email-jarod@redhat.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=98581


Reported-by: default avatarJarod Wilson <jarod@redhat.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarJarod Wilson <jarod@redhat.com>
Tested-by: default avatarJarod Wilson <jarod@redhat.com>
parent 5ebe6afa

drivers/pci/hotplug/Makefile

+0 −3
Original line number Diff line number Diff line
@@ -61,9 +61,6 @@ pciehp-objs := pciehp_core.o \ 
				pciehp_ctrl.o	\

				pciehp_pci.o	\

				pciehp_hpc.o

ifdef CONFIG_ACPI

pciehp-objs		+=	pciehp_acpi.o

endif



shpchp-objs		:=	shpchp_core.o	\

				shpchp_ctrl.o	\

drivers/pci/hotplug/pciehp.h

+0 −17
Original line number Diff line number Diff line
@@ -167,21 +167,4 @@ static inline const char *slot_name(struct slot *slot) 
	return hotplug_slot_name(slot->hotplug_slot);

}



#ifdef CONFIG_ACPI

#include <linux/pci-acpi.h>



void __init pciehp_acpi_slot_detection_init(void);

int pciehp_acpi_slot_detection_check(struct pci_dev *dev);



static inline void pciehp_firmware_init(void)

{

	pciehp_acpi_slot_detection_init();

}

#else

#define pciehp_firmware_init()				do {} while (0)

static inline int pciehp_acpi_slot_detection_check(struct pci_dev *dev)

{

	return 0;

}

#endif				/* CONFIG_ACPI */

#endif				/* _PCIEHP_H */

drivers/pci/hotplug/pciehp_acpi.c

deleted100644 → 0
+0 −137
Original line number Diff line number Diff line 
/*

 * ACPI related functions for PCI Express Hot Plug driver.

 *

 * Copyright (C) 2008 Kenji Kaneshige

 * Copyright (C) 2008 Fujitsu Limited.

 *

 * All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or (at

 * your option) any later version.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or

 * NON INFRINGEMENT.  See the GNU General Public License for more

 * details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 *

 */



#include <linux/acpi.h>

#include <linux/pci.h>

#include <linux/pci_hotplug.h>

#include <linux/slab.h>

#include <linux/module.h>

#include "pciehp.h"



#define PCIEHP_DETECT_PCIE	(0)

#define PCIEHP_DETECT_ACPI	(1)

#define PCIEHP_DETECT_AUTO	(2)

#define PCIEHP_DETECT_DEFAULT	PCIEHP_DETECT_AUTO



struct dummy_slot {

	u32 number;

	struct list_head list;

};



static int slot_detection_mode;

static char *pciehp_detect_mode;

module_param(pciehp_detect_mode, charp, 0444);

MODULE_PARM_DESC(pciehp_detect_mode,

	 "Slot detection mode: pcie, acpi, auto\n"

	 "  pcie          - Use PCIe based slot detection\n"

	 "  acpi          - Use ACPI for slot detection\n"

	 "  auto(default) - Auto select mode. Use acpi option if duplicate\n"

	 "                  slot ids are found. Otherwise, use pcie option\n");



int pciehp_acpi_slot_detection_check(struct pci_dev *dev)

{

	if (slot_detection_mode != PCIEHP_DETECT_ACPI)

		return 0;

	if (acpi_pci_detect_ejectable(ACPI_HANDLE(&dev->dev)))

		return 0;

	return -ENODEV;

}



static int __init parse_detect_mode(void)

{

	if (!pciehp_detect_mode)

		return PCIEHP_DETECT_DEFAULT;

	if (!strcmp(pciehp_detect_mode, "pcie"))

		return PCIEHP_DETECT_PCIE;

	if (!strcmp(pciehp_detect_mode, "acpi"))

		return PCIEHP_DETECT_ACPI;

	if (!strcmp(pciehp_detect_mode, "auto"))

		return PCIEHP_DETECT_AUTO;

	warn("bad specifier '%s' for pciehp_detect_mode. Use default\n",

	     pciehp_detect_mode);

	return PCIEHP_DETECT_DEFAULT;

}



static int __initdata dup_slot_id;

static int __initdata acpi_slot_detected;

static struct list_head __initdata dummy_slots = LIST_HEAD_INIT(dummy_slots);



/* Dummy driver for duplicate name detection */

static int __init dummy_probe(struct pcie_device *dev)

{

	u32 slot_cap;

	acpi_handle handle;

	struct dummy_slot *slot, *tmp;

	struct pci_dev *pdev = dev->port;



	pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, &slot_cap);

	slot = kzalloc(sizeof(*slot), GFP_KERNEL);

	if (!slot)

		return -ENOMEM;

	slot->number = (slot_cap & PCI_EXP_SLTCAP_PSN) >> 19;

	list_for_each_entry(tmp, &dummy_slots, list) {

		if (tmp->number == slot->number)

			dup_slot_id++;

	}

	list_add_tail(&slot->list, &dummy_slots);

	handle = ACPI_HANDLE(&pdev->dev);

	if (!acpi_slot_detected && acpi_pci_detect_ejectable(handle))

		acpi_slot_detected = 1;

	return -ENODEV;         /* dummy driver always returns error */

}



static struct pcie_port_service_driver __initdata dummy_driver = {

	.name		= "pciehp_dummy",

	.port_type	= PCIE_ANY_PORT,

	.service	= PCIE_PORT_SERVICE_HP,

	.probe		= dummy_probe,

};



static int __init select_detection_mode(void)

{

	struct dummy_slot *slot, *tmp;



	if (pcie_port_service_register(&dummy_driver))

		return PCIEHP_DETECT_ACPI;

	pcie_port_service_unregister(&dummy_driver);

	list_for_each_entry_safe(slot, tmp, &dummy_slots, list) {

		list_del(&slot->list);

		kfree(slot);

	}

	if (acpi_slot_detected && dup_slot_id)

		return PCIEHP_DETECT_ACPI;

	return PCIEHP_DETECT_PCIE;

}



void __init pciehp_acpi_slot_detection_init(void)

{

	slot_detection_mode = parse_detect_mode();

	if (slot_detection_mode != PCIEHP_DETECT_AUTO)

		goto out;

	slot_detection_mode = select_detection_mode();

out:

	if (slot_detection_mode == PCIEHP_DETECT_ACPI)

		info("Using ACPI for slot detection.\n");

}

drivers/pci/hotplug/pciehp_core.c

+3 −7
Original line number Diff line number Diff line
@@ -248,12 +248,9 @@ static int pciehp_probe(struct pcie_device *dev) 
	struct slot *slot;

	u8 occupied, poweron;



	if (pciehp_force)

		dev_info(&dev->device,

			 "Bypassing BIOS check for pciehp use on %s\n",

			 pci_name(dev->port));

	else if (pciehp_acpi_slot_detection_check(dev->port))

		goto err_out_none;

	/* If this is not a "hotplug" service, we have no business here. */

	if (dev->service != PCIE_PORT_SERVICE_HP)

		return -ENODEV;



	if (!dev->port->subordinate) {

		/* Can happen if we run out of bus numbers during probe */
@@ -366,7 +363,6 @@ static int __init pcied_init(void) 
{

	int retval = 0;



	pciehp_firmware_init();

	retval = pcie_port_service_register(&hpdriver_portdrv);

	dbg("pcie_port_service_register = %d\n", retval);

	info(DRIVER_DESC " version: " DRIVER_VERSION "\n");