Fwd: [Bug 99751] New: Enormous resume delay, unless pcie_ports=compat

[Bjorn Helgaas <bhelgaas@google.com>]

FYI.  There's more information and analysis, but no resolution yet, in
the bugzilla.


---------- Forwarded message ----------
From:  <bugzilla-daemon@bugzilla.kernel.org>
Date: Wed, Jun 10, 2015 at 11:25 AM
Subject: [Bug 99751] New: Enormous resume delay, unless pcie_ports=compat
To: bhelgaas@google.com


https://bugzilla.kernel.org/show_bug.cgi?id=99751

            Bug ID: 99751
           Summary: Enormous resume delay, unless pcie_ports=compat
           Product: Drivers
           Version: 2.5
    Kernel Version: 3.15 through 4.1rc5
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: PCI
          Assignee: drivers_pci@kernel-bugs.osdl.org
          Reporter: lenb@kernel.org
        Regression: No

Created attachment 179451
  --> https://bugzilla.kernel.org/attachment.cgi?id=179451&action=edit
lspci -vvv output

On a Dell XPS11 laptop, pcieport 0000:00:1c.0 takes
several seconds to resume from suspend.

Booting with "pcie_ports=compat", or
building with  CONFIG_HOTPLUG_PCI_PCIE=n
makes this delay go away.

I've tested Linux-3.14.44 and do not see this delay.
I've tested Linux-3.15.0 and others up through 4.1-rc5
and I do see this delay.  So I'll mark this as a regression.

while I use analyze_suspend.py to trace resume,
initcall_debug is sufficient to show this delay in dmesg,
and I notice some additional PCI warnings there:

[   55.897986] pciehp 0000:00:1c.0:pcie04: Link Training Error occurs
[   55.897988] pciehp 0000:00:1c.0:pcie04: Failed to check link status
[   55.897992] call 0000:00:1c.0+ returned 0 after 2197660 usecs

(yes, that is 2.19 SECONDS -- where anything> 50ms for resume is considered
slow)

Unclear (to me) what pcie04 is...

$ lspci
00:00.0 Host bridge: Intel Corporation Haswell-ULT DRAM Controller (rev 0b)
00:02.0 VGA compatible controller: Intel Corporation Device 0a1e (rev 0b)
00:03.0 Audio device: Intel Corporation Haswell-ULT HD Audio Controller (rev
0b)
00:04.0 Signal processing controller: Intel Corporation Device 0a03 (rev 0b)
00:14.0 USB controller: Intel Corporation 8 Series USB xHCI HC (rev 04)
00:16.0 Communication controller: Intel Corporation 8 Series HECI #0 (rev 04)
00:1b.0 Audio device: Intel Corporation 8 Series HD Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 1 (rev e4)
00:1c.1 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 2 (rev e4)
00:1c.3 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 4 (rev e4)
00:1d.0 USB controller: Intel Corporation 8 Series USB EHCI #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation 8 Series LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 8 Series SATA Controller 1 [AHCI
mode] (rev 04)
00:1f.3 SMBus: Intel Corporation 8 Series SMBus Controller (rev 04)
00:1f.6 Signal processing controller: Intel Corporation 8 Series Thermal (rev
04)
05:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5249 PCI
Express Card Reader (rev 01)
07:00.0 Network controller: Intel Corporation Wireless 7260 (rev 6b)

This 04 item appears under 1c.0 when I ask lspci about topology:
$ lspci -tv
-[0000:00]-+-00.0  Intel Corporation Haswell-ULT DRAM Controller
           +-02.0  Intel Corporation Device 0a1e
           +-03.0  Intel Corporation Haswell-ULT HD Audio Controller
           +-04.0  Intel Corporation Device 0a03
           +-14.0  Intel Corporation 8 Series USB xHCI HC
           +-16.0  Intel Corporation 8 Series HECI #0
           +-1b.0  Intel Corporation 8 Series HD Audio Controller
           +-1c.0-[04]--
           +-1c.1-[05]----00.0  Realtek Semiconductor Co., Ltd. RTS5249 PCI
Express Card Reader
           +-1c.3-[07]----00.0  Intel Corporation Wireless 7260
           +-1d.0  Intel Corporation 8 Series USB EHCI #1
           +-1f.0  Intel Corporation 8 Series LPC Controller
           +-1f.2  Intel Corporation 8 Series SATA Controller 1 [AHCI mode]
           +-1f.3  Intel Corporation 8 Series SMBus Controller
           \-1f.6  Intel Corporation 8 Series Thermal

--
You are receiving this mail because:
You are watching the assignee of the bug.