[Bug 208891] Thunderbolt hotplug fails on HP x360 13t-aw000/86FA with HP Thunderbolt 3 Dock

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=208891

--- Comment #12 from Matt Turner (mattst88@gmail.com) ---
With some help from Ben Widawsky, we noticed that PCI device 2d:04.0 (Intel
Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015] [8086:1578])
doesn't get IO space allocated correctly on hotplug:

mattst88@hp-x360 ~ % head working 
2d:04.0 PCI bridge [0604]: Intel Corporation DSL6540 Thunderbolt 3 Bridge
[Alpine Ridge 4C 2015] [8086:1578] (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort-
<MAbort- >SERR- <PERR- INTx-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 144
        Bus: primary=2d, secondary=32, subordinate=32, sec-latency=0
        I/O behind bridge: 00005000-00005fff [size=4K]
        Memory behind bridge: [disabled]
        Prefetchable memory behind bridge: [disabled]
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort-
<MAbort- <SERR- <PERR-
mattst88@hp-x360 ~ % head broken    
2d:04.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine
Ridge 4C 2015] (prog-if 00 [Normal decode])
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort-
<MAbort- >SERR- <PERR- INTx-
        Latency: 0
        Interrupt: pin A routed to IRQ 169
        Bus: primary=2d, secondary=32, subordinate=56, sec-latency=0
        I/O behind bridge: [disabled]
        Memory behind bridge: 68400000-741fffff [size=190M]
        Prefetchable memory behind bridge: 0000006000400000-000000601bffffff
[size=444M]
        Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort-
<MAbort- <SERR- <PERR-


Additionally, when I do 'echo 1 > /sys/bus/pci/rescan' I see this in dmesg:

[Aug12 15:37] pcieport 0000:2d:04.0: bridge window [io  0x1000-0x0fff] to [bus
32-56] add_size 1000
[  +0.000006] pcieport 0000:2d:04.0: BAR 7: no space for [io  size 0x1000]
[  +0.000001] pcieport 0000:2d:04.0: BAR 7: failed to assign [io  size 0x1000]
[  +0.000001] pcieport 0000:2d:04.0: BAR 7: no space for [io  size 0x1000]
[  +0.000000] pcieport 0000:2d:04.0: BAR 7: failed to assign [io  size 0x1000]
[  +0.079302] pci_bus 0000:2e: Allocating resources
[  +0.000017] pci_bus 0000:2f: Allocating resources
[  +0.000016] pci_bus 0000:30: Allocating resources
[  +0.000009] pci_bus 0000:31: Allocating resources
[  +0.000085] pci_bus 0000:2e: Allocating resources
[  +0.000015] pci_bus 0000:2f: Allocating resources
[  +0.000015] pci_bus 0000:30: Allocating resources
[  +0.000010] pci_bus 0000:31: Allocating resources

which seems to corroborate that point.

And 2d:04 appears to be a critical device in the tree, according to lspci -t:

           +-07.1-[2c-56]----00.0-[2d-56]--+-00.0-[2e]----00.0  ASMedia
Technology Inc. ASM1042A USB 3.0 Host Controller [1b21:1142]
           |                               +-01.0-[2f]----00.0  Broadcom Inc.
and subsidiaries NetXtreme BCM57762 Gigabit Ethernet PCIe [14e4:1682]
           |                               +-02.0-[30]--
           |                               +-03.0-[31]--
           |                               \-04.0-[32-56]--

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