Messages in this thread | | | Subject | Re: [PATCH] thunderbolt: Add support for INTEL_FALCON_RIDGE_2C controller | From | Xavier Gnata <> | Date | Wed, 13 Jul 2016 23:46:30 +0200 |
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> 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: > http://i.imgur.com/ItIqxDY.png > > 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: > https://github.com/l1k/linux/commit/8148c395ef6e > > 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: > https://github.com/l1k/linux/commit/c596932608cd > > 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: > https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1170039.html > > 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 https://github.com/l1k/linux/commit/c596932608cd : 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 :)
Xavier
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