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PCI: pciehp: Tolerate Presence Detect hardwired to zero 

The WiGig Bus Extension (WBE) specification allows tunneling PCIe over
IEEE 802.11.  A product implementing this spec is the wil6210 from
Wilocity (now part of Qualcomm Atheros).  It integrates a PCIe switch
with a wireless network adapter:

  00.0-+              [1ae9:0101]  Upstream Port
       +-00.0-+       [1ae9:0200]  Downstream Port
       |      +-00.0  [168c:0034]  Atheros AR9462 Wireless Network Adapter
       +-02.0         [1ae9:0201]  Downstream Port
       +-03.0         [1ae9:0201]  Downstream Port

Wirelessly attached devices presumably appear below the hotplug ports
with device ID [1ae9:0201].  Oddly, the Downstream Port [1ae9:0200]
leading to the wireless network adapter is likewise Hotplug Capable,
but has its Presence Detect State bit hardwired to zero.  Even if the
Link Active bit is set, Presence Detect is zero, so this cannot be
caused by in-band presence detection but only by broken hardware.

pciehp assumes an empty slot if Presence Detect State is zero,
regardless of Link Active being one.  Consequently, up until v4.18 it
removes the wireless network adapter in pciehp_resume().  From v4.19 it
already does so in pciehp_probe().

Be lenient towards broken hardware and assume the slot is occupied if
Link Active is set:  Introduce pciehp_card_present_or_link_active()
and use it in lieu of pciehp_get_adapter_status() everywhere, except
in pciehp_handle_presence_or_link_change() whose log messages depend
on which of Presence Detect State or Link Active is set.

Remove the Presence Detect State check from __pciehp_enable_slot()
because it is only called if either of Presence Detect State or Link
Active is set.

Caution: There is a possibility that broken hardware exists which has
working Presence Detect but hardwires Link Active to one.  On such
hardware the slot will now incorrectly be considered always occupied.
If such hardware is discovered, this commit can be rolled back and a
quirk can be added which sets is_hotplug_bridge = 0 for [1ae9:0200].

Link: https://bugzilla.kernel.org/show_bug.cgi?id=200839
Reported-and-tested-by: David Yang <mmyangfl@gmail.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Rajat Jain <rajatja@google.com>
Cc: Ashok Raj <ashok.raj@intel.com>
This commit is contained in:
Lukas Wunner 2018-09-08 09:59:01 +02:00 committed by Bjorn Helgaas
parent eee6e27384
commit 80696f9914
4 changed files with 26 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/pci/hotplug/pciehp.h
View File

@ -190,11 +190,12 @@ void pciehp_get_power_status(struct slot *slot, u8 *status);
void pciehp_set_attention_status(struct slot *slot, u8 status);
void pciehp_get_latch_status(struct slot *slot, u8 *status);
void pciehp_get_adapter_status(struct slot *slot, u8 *status);
int pciehp_query_power_fault(struct slot *slot);
void pciehp_green_led_on(struct slot *slot);
void pciehp_green_led_off(struct slot *slot);
void pciehp_green_led_blink(struct slot *slot);
bool pciehp_card_present(struct controller *ctrl);
bool pciehp_card_present_or_link_active(struct controller *ctrl);
int pciehp_check_link_status(struct controller *ctrl);
bool pciehp_check_link_active(struct controller *ctrl);
void pciehp_release_ctrl(struct controller *ctrl);

6
drivers/pci/hotplug/pciehp_core.c
View File

@ -158,7 +158,7 @@ static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
struct pci_dev *pdev = slot->ctrl->pcie->port;
pci_config_pm_runtime_get(pdev);
pciehp_get_adapter_status(slot, value);
*value = pciehp_card_present_or_link_active(slot->ctrl);
pci_config_pm_runtime_put(pdev);
return 0;
}
@ -176,12 +176,12 @@ static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
static void pciehp_check_presence(struct controller *ctrl)
{
struct slot *slot = ctrl->slot;
u8 occupied;
bool occupied;
down_read(&ctrl->reset_lock);
mutex_lock(&slot->lock);
pciehp_get_adapter_status(slot, &occupied);
occupied = pciehp_card_present_or_link_active(ctrl);
if ((occupied && (slot->state == OFF_STATE ||
slot->state == BLINKINGON_STATE)) ||
(!occupied && (slot->state == ON_STATE ||

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

@ -223,8 +223,7 @@ void pciehp_handle_disable_request(struct slot *slot)
void pciehp_handle_presence_or_link_change(struct slot *slot, u32 events)
{
struct controller *ctrl = slot->ctrl;
bool link_active;
u8 present;
bool present, link_active;
/*
* If the slot is on and presence or link has changed, turn it off.
@ -253,7 +252,7 @@ void pciehp_handle_presence_or_link_change(struct slot *slot, u32 events)
/* Turn the slot on if it's occupied or link is up */
mutex_lock(&slot->lock);
pciehp_get_adapter_status(slot, &present);
present = pciehp_card_present(ctrl);
link_active = pciehp_check_link_active(ctrl);
if (!present && !link_active) {
mutex_unlock(&slot->lock);
@ -286,11 +285,6 @@ static int __pciehp_enable_slot(struct slot *p_slot)
u8 getstatus = 0;
struct controller *ctrl = p_slot->ctrl;
pciehp_get_adapter_status(p_slot, &getstatus);
if (!getstatus) {
ctrl_info(ctrl, "Slot(%s): No adapter\n", slot_name(p_slot));
return -ENODEV;
}
if (MRL_SENS(p_slot->ctrl)) {
pciehp_get_latch_status(p_slot, &getstatus);
if (getstatus) {

25
drivers/pci/hotplug/pciehp_hpc.c
View File

@ -389,13 +389,27 @@ void pciehp_get_latch_status(struct slot *slot, u8 *status)
*status = !!(slot_status & PCI_EXP_SLTSTA_MRLSS);
}
void pciehp_get_adapter_status(struct slot *slot, u8 *status)
bool pciehp_card_present(struct controller *ctrl)
{
struct pci_dev *pdev = ctrl_dev(slot->ctrl);
struct pci_dev *pdev = ctrl_dev(ctrl);
u16 slot_status;
pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
*status = !!(slot_status & PCI_EXP_SLTSTA_PDS);
return slot_status & PCI_EXP_SLTSTA_PDS;
}
/**
* pciehp_card_present_or_link_active() - whether given slot is occupied
* @ctrl: PCIe hotplug controller
*
* Unlike pciehp_card_present(), which determines presence solely from the
* Presence Detect State bit, this helper also returns true if the Link Active
* bit is set. This is a concession to broken hotplug ports which hardwire
* Presence Detect State to zero, such as Wilocity's [1ae9:0200].
*/
bool pciehp_card_present_or_link_active(struct controller *ctrl)
{
return pciehp_card_present(ctrl) || pciehp_check_link_active(ctrl);
}
int pciehp_query_power_fault(struct slot *slot)
@ -858,7 +872,7 @@ struct controller *pcie_init(struct pcie_device *dev)
{
struct controller *ctrl;
u32 slot_cap, link_cap;
u8 occupied, poweron;
u8 poweron;
struct pci_dev *pdev = dev->port;
ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL);
@ -918,9 +932,8 @@ struct controller *pcie_init(struct pcie_device *dev)
* requested yet, so avoid triggering a notification with this command.
*/
if (POWER_CTRL(ctrl)) {
pciehp_get_adapter_status(ctrl->slot, &occupied);
pciehp_get_power_status(ctrl->slot, &poweron);
if (!occupied && poweron) {
if (!pciehp_card_present_or_link_active(ctrl) && poweron) {
pcie_disable_notification(ctrl);
pciehp_power_off_slot(ctrl->slot);
}