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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: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jarod Wilson <jarod@redhat.com>
Tested-by: Jarod Wilson <jarod@redhat.com>
This commit is contained in:
Rafael J. Wysocki 2015-05-19 15:27:58 +02:00 committed by Bjorn Helgaas
parent 5ebe6afaf0
commit e705c2959b
4 changed files with 3 additions and 164 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/pci/hotplug/Makefile
View File

@ -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 \

17
drivers/pci/hotplug/pciehp.h
View File

@ -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 */

137
drivers/pci/hotplug/pciehp_acpi.c
View File

@ -1,137 +0,0 @@
/*
* 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");
}

10
drivers/pci/hotplug/pciehp_core.c
View File

@ -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");