From: Bjorn Helgaas <helgaas@kernel.org>
To: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
Cc: linux-pci@vger.kernel.org,
Blazej Kucman <blazej.kucman@intel.com>,
Hans de Goede <hdegoede@redhat.com>,
Lukas Wunner <lukas@wunner.de>,
Naveen Naidu <naveennaidu479@gmail.com>,
Keith Busch <kbusch@kernel.org>,
Nirmal Patel <nirmal.patel@linux.intel.com>,
Jonathan Derrick <jonathan.derrick@linux.dev>
Subject: Re: [Bug 215525] New: HotPlug does not work on upstream kernel 5.17.0-rc1
Date: Thu, 27 Jan 2022 20:52:12 -0600 [thread overview]
Message-ID: <20220128025212.GA152555@bhelgaas> (raw)
In-Reply-To: <20220127154615.00003df8@linux.intel.com>
On Thu, Jan 27, 2022 at 03:46:15PM +0100, Mariusz Tkaczyk wrote:
> ...
> Thanks for your suggestions. Blazej did some tests and results were
> inconclusive. He tested it on two same platforms. On the first one it
> didn't work, even if he reverted all suggested patches. On the second
> one hotplugs always worked.
>
> He noticed that on first platform where issue has been found initally,
> there was boot parameter "pci=nommconf". After adding this parameter
> on the second platform, hotplugs stopped working too.
>
> Tested on tag pci-v5.17-changes. He have CONFIG_HOTPLUG_PCI_PCIE
> and CONFIG_DYNAMIC_DEBUG enabled in config. He also attached two dmesg
> logs to bugzilla with boot parameter 'dyndbg="file pciehp* +p" as
> requested. One with "pci=nommconf" and one without.
>
> Issue seems to related to "pci=nommconf" and it is probably caused
> by change outside pciehp.
Maybe I'm missing something. If I understand correctly, the problem
has nothing to do with the kernel version (correct me if I'm wrong!)
PCIe native hotplug doesn't work when booted with "pci=nommconf".
When using "pci=nommconf", obviously we can't access the extended PCI
config space (offset 0x100-0xfff), so none of the extended
capabilities are available.
In that case, we don't even ask the platform for control of PCIe
hotplug via _OSC. From the dmesg diff from normal (working) to
"pci=nommconf" (not working):
-Command line: BOOT_IMAGE=/boot/vmlinuz-smp ...
+Command line: BOOT_IMAGE=/boot/vmlinuz-smp pci=nommconf ...
...
-acpi PNP0A08:00: _OSC: OS supports [ExtendedConfig ASPM ClockPM Segments MSI HPX-Type3]
-acpi PNP0A08:00: _OSC: platform does not support [AER LTR]
-acpi PNP0A08:00: _OSC: OS now controls [PCIeHotplug PME PCIeCapability]
+acpi PNP0A08:00: _OSC: OS supports [ASPM ClockPM Segments MSI HPX-Type3]
+acpi PNP0A08:00: _OSC: not requesting OS control; OS requires [ExtendedConfig ASPM ClockPM MSI]
+acpi PNP0A08:00: MMCONFIG is disabled, can't access extended PCI configuration space under this bridge.
Why are you using "pci=nommconf"? As far as I know, there's no reason
to use that except to work around some kind of defect.
Bjorn
next prev parent reply other threads:[~2022-01-28 2:52 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-215525-41252@https.bugzilla.kernel.org/>
2022-01-24 21:46 ` [Bug 215525] New: HotPlug does not work on upstream kernel 5.17.0-rc1 Bjorn Helgaas
2022-01-25 8:58 ` Hans de Goede
2022-01-25 15:33 ` Lukas Wunner
2022-01-26 7:31 ` Thorsten Leemhuis
2022-01-27 14:46 ` Mariusz Tkaczyk
2022-01-27 20:47 ` Jonathan Derrick
2022-01-27 22:31 ` Jonathan Derrick
2022-01-28 2:52 ` Bjorn Helgaas [this message]
2022-01-28 8:29 ` Mariusz Tkaczyk
2022-01-28 13:08 ` Bjorn Helgaas
2022-01-28 13:49 ` Kai-Heng Feng
2022-01-28 14:03 ` Bjorn Helgaas
2022-02-02 15:48 ` Blazej Kucman
2022-02-02 16:43 ` Bjorn Helgaas
2022-02-03 9:13 ` Thorsten Leemhuis
2022-02-03 10:47 ` Blazej Kucman
2022-02-03 15:58 ` Bjorn Helgaas
2022-02-09 13:41 ` Blazej Kucman
2022-02-09 21:02 ` Bjorn Helgaas
2022-02-10 11:14 ` Blazej Kucman
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