PCIe Hotplug for Thunderbolt and U.2

[Jeremy Soller]

This is to continue the discussion from the coreboot leadership meeting. Thunderbolt devices are not correctly initialized by Coreboot such that the OS can boot without kernel parameters and allow for Thunderbolt hotplugging. Additional bus numbers and memory must be allocated.

I will be working on support for this for our System76 mainboards.

Here were the notes taken about it during the meeting, see 9 October 2019, PCIe Hotplug on newer Intel socs:

https://docs.google.com/document/d/1NRXqXcLBp5pFkHiJbrLdv3Spqh1Hu086HYkKrgKj...

[Aaron Durbin]

Please include intel and google on your patches because we'll be needing
this support in the near future as well. The allocator limitations are
known, and Kyosti and I have talked about improving things here. As for the
children comment you need to reserve a sufficiently large mmio space and in
the hotplug path one can allocate subdevices. Since it's inherently a
hotplug there's no way to know what the topology will be when a device is
plugged in.

On Wed, Oct 9, 2019 at 12:32 PM Jeremy Soller  wrote:
> This is to continue the discussion from the coreboot leadership meeting.
> Thunderbolt devices are not correctly initialized by Coreboot such that the
> OS can boot without kernel parameters and allow for Thunderbolt
> hotplugging. Additional bus numbers and memory must be allocated.
>
> I will be working on support for this for our System76 mainboards.
>
> Here were the notes taken about it during the meeting, see 9 October 2019,
> PCIe Hotplug on newer Intel socs:
>
> https://docs.google.com/document/d/1NRXqXcLBp5pFkHiJbrLdv3Spqh1Hu086HYkKrgKj...

[Jeremy Soller]

Will do. Any relevant emails I should CC when I have something?

[Aaron Durbin]

On Wed, Oct 9, 2019 at 3:07 PM Jeremy Soller  wrote:
> Will do. Any relevant emails I should CC when I have something?

I'm not sure about Intel, but you can include mine, Duncan's, and
Furquan's. Should be autocomplete in gerrit.
> On Wed, Oct 9, 2019, at 1:29 PM, Aaron Durbin wrote:
>
> Please include intel and google on your patches because we'll be needing
> this support in the near future as well. The allocator limitations are
> known, and Kyosti and I have talked about improving things here. As for the
> children comment you need to reserve a sufficiently large mmio space and in
> the hotplug path one can allocate subdevices. Since it's inherently a
> hotplug there's no way to know what the topology will be when a device is
> plugged in.
>
> On Wed, Oct 9, 2019 at 12:32 PM Jeremy Soller  wrote:
>
> This is to continue the discussion from the coreboot leadership meeting.
> Thunderbolt devices are not correctly initialized by Coreboot such that the
> OS can boot without kernel parameters and allow for Thunderbolt
> hotplugging. Additional bus numbers and memory must be allocated.
>
> I will be working on support for this for our System76 mainboards.
>
> Here were the notes taken about it during the meeting, see 9 October 2019,
> PCIe Hotplug on newer Intel socs:
>
> https://docs.google.com/document/d/1NRXqXcLBp5pFkHiJbrLdv3Spqh1Hu086HYkKrgKj...

[Jeremy Soller]

Thanks, I will probably have a patch sometime tomorrow.

[Jeremy Soller]

Here is the patch: https://review.coreboot.org/c/coreboot/+/35946

[Jeremy Soller]

Hello All,

I have done significant cleanup on my previous patch that I think will be useful for the USB4 patch. It is now generic for any PCIe hotplug bridge, and the resources allocated are configurable with sane defaults (from our requirements for Thunderbolt 3).

https://review.coreboot.org/c/coreboot/+/35946/2

From Intel side please include Divya Sasidharan and me

[e-mail]
[e-mail]

Thanks,
Brandon