diff options
| author | Lukas Wunner <lukas@wunner.de> | 2018-09-08 09:59:01 +0200 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2018-09-18 17:52:15 -0500 |
| commit | 80696f991424d05a784c0cf9c314ac09ac280406 (patch) | |
| tree | 9fa62d14164d59c087fb6cac1d7ec8069ce8c05b /drivers/pci/hotplug/pciehp_ctrl.c | |
| parent | eee6e273843dc3084c15efc98a78702ac9a4c69b (diff) | |
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>
Diffstat (limited to 'drivers/pci/hotplug/pciehp_ctrl.c')
| -rw-r--r-- | drivers/pci/hotplug/pciehp_ctrl.c | 10 |
1 files changed, 2 insertions, 8 deletions
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c index c4d0f902f1d2..1fda6ea96fdc 100644 --- a/drivers/pci/hotplug/pciehp_ctrl.c +++ b/drivers/pci/hotplug/pciehp_ctrl.c @@ -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) { |