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SubjectRe: [PATCH] thunderbolt: Add support for INTEL_FALCON_RIDGE_2C controller

> On Wed, Jul 13, 2016 at 12:17:33AM +0200, Andreas Noever wrote:
>> Are thunderbolt controllers always installed directly below the root
>> port? In theory there could be more bridges in between (a candidate
>> for such a topology would be the mac pro which has 3 controllers).
> Hm, good point. I failed to find lspci or dmesg output for a MacPro6,1
> but I did find this diagram:
> Turns out the 3 controllers are connected to a PCIe switch.
> And according to the PCIe spec, a switch consists of an upstream
> bridge and downstream bridges. So the parent of the Thunderbolt
> upstream port would be a downstream port and not a root port. :-/
> Another idea would be to detect if the parent of the Thunderbolt
> upstream port has the VSEC 0x1234. This is only present on Thunderbolt
> devices, so a host controller is identifiable by the non-presence of
> that VSEC on its parent. Patch [01/13] of my runpm series adds a
> convenient is_thunderbolt flag to detect the VSEC:
> Generally I think it would be beneficial to replace the PCI quirk
> with code that lives in drivers/thunderbolt/. Here's an example what
> I have in mind, this is based on top of the runpm series and ensures
> that the NHI resumes before the hotplug ports by waking it directly
> from the upstream bridge:
> An even better approach would probably be Rafael's "device links"
> series which allows the PM core to take care of device dependencies
> beyond the mere parent/child relationship:
> Best regards,
> Lukas
I agree that it would be a good idea to get rid of both the subsystem
vendor/device id and the quirk.
I quite like the approach of : Do you want me to
give it a try on my hardware?
Rafael's approach is more ambitious and complex but even cleaner.
Maybe a two step approach : First we get rid of the quirk and we support
INTEL_FALCON_RIDGE_2C controller and, in a longer run, we try to
implement these functional dependencies in PCI core.
Anyway you are the experts :)


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