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Re: [PATCH v2 02/10] driver core: Functional dependencies tracking support

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On Friday, June 17, 2016 04:07:38 PM Lukas Wunner wrote:
> On Fri, Jun 17, 2016 at 02:54:56PM +0200, Rafael J. Wysocki wrote:
> > On Fri, Jun 17, 2016 at 12:36 PM, Lukas Wunner <lukas@wunner.de> wrote:
> > > On Fri, Jun 17, 2016 at 08:26:52AM +0200, Marek Szyprowski wrote:
> > > > From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> > > We also have such a functional dependency for Thunderbolt on Macs:
> > > On resume from system sleep, the PCIe hotplug ports may not resume
> > > before the thunderbolt driver has reestablished the PCI tunnels.
> > > Currently this is enforced by quirk_apple_wait_for_thunderbolt()
> > > in drivers/pci/quirks.c. It would be good if we could represent
> > > this dependency using something like Rafael's approach instead of
> > > open coding it, however one detail in Rafael's patches is problematic:
> > >
> > > > New links are added by calling device_link_add() which may happen
> > > > either before the consumer device is probed or when probing it, in
> > > > which case the caller needs to ensure that the driver of the
> > > > supplier device is present and functional and the DEVICE_LINK_PROBE_TIME
> > > > flag should be passed to device_link_add() to reflect that.
> > >
> > > The thunderbolt driver cannot call device_link_add() before the
> > > PCIe hotplug ports are bound to a driver unless we amend portdrv
> > > to return -EPROBE_DEFER for Thunderbolt hotplug ports on Macs
> > > if the thunderbolt driver isn't loaded.
> > >
> > > It would therefore be beneficial if device_link_add() can be
> > > called even *after* the consumer is bound.
> > 
> > I don't quite follow.
> > 
> > Who's the provider and who's the consumer here?
> 
> thunderbolt.ko is the supplier.

But it binds to the children of the ports that are supposed to be its
consumers?

Why is that even expected to work?

Thanks,
Rafael

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Re: [PATCH v2 02/10] driver core: Functional dependencies tracking support "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-07-20 02:30 +0200
  Re: [PATCH v2 02/10] driver core: Functional dependencies tracking  support Lukas Wunner <lukas@wunner.de> - 2016-07-20 08:30 +0200
    Re: [PATCH v2 02/10] driver core: Functional dependencies tracking support "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-07-20 14:50 +0200
      Re: [PATCH v2 02/10] driver core: Functional dependencies tracking  support Lukas Wunner <lukas@wunner.de> - 2016-07-20 17:30 +0200
        Re: [PATCH v2 02/10] driver core: Functional dependencies tracking support "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-07-21 00:50 +0200
          Re: [PATCH v2 02/10] driver core: Functional dependencies tracking  support Lukas Wunner <lukas@wunner.de> - 2016-07-21 01:30 +0200
            Re: [PATCH v2 02/10] driver core: Functional dependencies tracking support "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-07-21 02:30 +0200
              Re: [PATCH v2 02/10] driver core: Functional dependencies tracking  support Lukas Wunner <lukas@wunner.de> - 2016-07-25 00:50 +0200

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