Re: [RFC 1/3] thunderbolt: Allow XHCI device links to enter runtime pm

From: Limonciello, Mario
Date: Tue Oct 04 2022 - 07:38:59 EST

On 10/4/2022 00:04, Mika Westerberg wrote:
Hi Mario,

On Mon, Oct 03, 2022 at 11:12:23PM -0500, Mario Limonciello wrote:
Both on Intel's and AMD's USB4 designs it's important that the device
link to the XHCI controller used for tunneling is able to go into D3
for appropriate low power consumption features as well as for system
suspend states such as s0i3.

Historically this is accomplished by adding to a hardcoded list in the
XHCI driver, but this requires a change for every single platform.

We have a very good proxy that it's safe to do this since the firmware
has indicated the device link needs to be made. So opt all XHCI
controllers with these device links into runtime PM.

This is good idea.

However, it misses the fact that we have FW CM as well in Intel
integrated TBT platforms (ICL, TGL and ADL) and with those you don't
have the device link (I think ADL has it for both, though) so we would
still need to keep the list in xHCI.

Can you double check the firmware for ADL for me whether it has it for both? I'll respin the series and drop at least the ICL and TGL reverts from patch 2.