Re: [Update][PATCH] PCIe / hotplug: Drop pointless ACPI-based "slot detection" check

[Jarod Wilson]

On 6/11/2015 5:16 PM, Rafael J. Wysocki wrote:
> On Thursday, June 11, 2015 04:38:12 PM Jarod Wilson wrote:
> > On 6/11/2015 1:05 PM, Jarod Wilson wrote:
> > > On 5/21/2015 9:21 PM, Rafael J. Wysocki wrote:
> > > > On Thursday, May 21, 2015 11:11:46 AM Bjorn Helgaas wrote:
> > > > > On Tue, May 19, 2015 at 03:27:58PM +0200, Rafael J. Wysocki wrote:
> > > > > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > > > > >
> > > > > > Jarod Wilson reports that the expresscard hotplug setup doesn't work
> > > > > > on HP ZBook G2.  The problem turns out to be the ACPI-based "slot
> > > > > > detection" code called from pciehp_probe() which tries to use some
> > > > > > questionable heuristics based on what ACPI objects are present for
> > > > > > the PCIe port device at hand to figure out whether or not to register
> > > > > > a hotplug slot for that port.
> > > > > >
> > > > > > That code is used if there is at least one PCIe port having an ACPI
> > > > > > device configuration object related to hotplug (such as _EJ0 or _RMV)
> > > > > > and the Thunderbolt port on the affected machine has _RMV.  Of course,
> > > > > > Thunderbolt and PCIe native hotplug need not be mutually exclusive
> > > > > > (as they aren't on the machine in question), so that rule is simply
> > > > > > incorrect.
> > > > > >
> > > > > > Moreover, the ACPI-based "slot detection" check does not add any
> > > > > > value if pciehp_probe() is called at all and the service type of the
> > > > > > device object it has been called for is PCIE_PORT_SERVICE_HP, because
> > > > > > PCIe hotplug services are only registered if the _OSC handshake in
> > > > > > acpi_pci_root_add() allows the kernel to control the PCIe native
> > > > > > hotplug feature.  No more checks need to be carried out to decide
> > > > > > whether or not to register a native PCIe hotlug slot in that case.
> > > > > >
> > > > > > For the above reasons, make pciehp_probe() check if it has been
> > > > > > called for the right service type and drop the pointless ACPI-based
> > > > > > "slot detection" check from it.  Also remove the entire code whose
> > > > > > only user is that check (the entire pciehp_acpi.c file goes away
> > > > > > as a result) and drop function headers related to it from the
> > > > > > internal PCIeHP header file.
> > > > > >
> > > > > > Link: http://marc.info/?t=143163219300002&r=1&w=2
> > > > > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=98581
> > > > > > Reported-by: Jarod Wilson <jarod@xxxxxxxxxx>
> > > > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > > > >
> > > > > This is awesome!  Applied to pci/hotplug for v4.2, with Jarod's
> > > > > reviewed/tested-by.
> > > >
> > > > Thanks!
> > >
> > > Looks like I didn't test enough. I can't explain WHY, but with this
> > > applied, now thunderbolt hot unplug of a network adapter goes haywire,
> > > where prior to the patch, it worked just fine. Still looking into it...
> >
> > Filed bug, dmesg spew can be found in the bug.
> >
> > https://bugzilla.kernel.org/show_bug.cgi?id=99841
>
> If it worked for you previously, can you possibly try to re-create that
> configuration and set of patches applied and retest then?

I tried the current Fedora 4.1-rc7 build first, everything was fine, 
then patched in JUST the one patch, and it went belly up. I'll add some 
extra debugging spew to a build both with and without the one patch, to 
see what differences there are in devices pciehp is claiming and follow 
up in the bug on your other info requests.

--
Jarod Wilson
jarod@xxxxxxxxxx
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