linux-kernel - Re: [PATCH v2 0/2] thunderbolt: Fix S4 resume incongruities

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Message-ID: <e821e8a1-8256-4f80-ab30-95f066d25946@panix.com>
Date: Mon, 19 Jan 2026 14:13:50 -0800
From: Kenneth Crudup <kenny@...ix.com>
To: "Mario Limonciello (AMD) (kernel.org)" <superm1@...nel.org>,
 "Katiyar, Pooja" <pooja.katiyar@...ux.intel.com>,
 Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc: "open list:THUNDERBOLT DRIVER" <linux-usb@...r.kernel.org>,
 linux-kernel@...r.kernel.org, Andreas Noever <andreas.noever@...il.com>,
 Yehezkel Bernat <YehezkelShB@...il.com>,
 Pooja Katiyar <pooja.katiyar@...el.com>,
 Rene Sapiens <rene.sapiens@...ux.intel.com>, Kenneth C <kenny@...ix.com>
Subject: Re: [PATCH v2 0/2] thunderbolt: Fix S4 resume incongruities

On 1/19/26 11:59, Mario Limonciello (AMD) (kernel.org) wrote:

> On 1/17/2026 10:57 AM, Katiyar, Pooja wrote:
> 
>>> I have confirmation the hack patch does help the issue for us too.
>>>
>>> If your patch doesn't work another logical solution could be to destroy
>>> all the tunnels as part of the PM freeze callback (not just the DP
>>> resources).  Maybe even unify the suspend and freeze codepaths for more
>>> opportunities for code reuse?
>>>
>>
>> Thanks for confirming the hack patch helps!
>>
>> We are actually working on a solution that releases the DP resources and
>> suspends the switch as part of the freeze sequence. This way the 
>> hibernation
>> image that is stored doesn't contain any active tunnels, and during 
>> resume
>> we get a DP hotplug notification for a new tunnel, similar to S5. So far
>> this patch is working fine but is under review.
>>
> 
> Thanks.  If you want early testing from us too before you're ready to 
> post publicly feel free to ping it offline to me too.

I'd like to get a CC: on that, too.

I've been testing that hack patch and will test further later tonight.

The issue I'm trying to chase down (and not sure if any of this will 
help with this, I wonder if it's really BIOS/EC related) is often times 
that after a suspend (or hibernate, but I use "suspend then hibernate", 
which I think does both and chooses which to use upon resume) and then 
connect to a different dock (or setup) from the one I'd suspended with, 
sometimes I have to unplug/replug my TB cable, otherwise I either get no 
recognition of my new display setup (and sometimes TB devices) or it'll 
try and use the same monitor resolution of the previously-connected 
monitor (as if the TB subsystem doesn't recognize things have changed).

-Kenny

-- 
Kenneth R. Crudup / Sr. SW Engineer, Scott County Consulting, Orange 
County CA