Re: "thunderbolt ... (DP): not active, tearing down" error breaking DP over thunderbolt displays

[Mika Westerberg <mika.westerberg@linux.intel.com>]

Hi,

On Sat, Oct 24, 2026 at 08:17:16PM +0200, Hans de Goede wrote:
> Hi All,
> 
> I hit this error:
> 
> Oct 24 19:16:58 x1 kernel: thunderbolt 0000:00:0d.3: 0:5 <-> 1:11 (DP): not active, tearing down
> 
> while doing some work on a Raptor Lake ThinkPad laptop plugged into a Thunderbolt dock.
> 
> After a bunch of debugging I found that the problem is that I had:
> 
> "UseSimpleDrm=1" in /etc/plymouth/plymouthd.conf, which combined with
> the latest dracut version causes dracut to omit the i915 drm driver
> from the initramfs.

The error means that the graphics driver did not read the monitor
capabilities in time (~12s) and therefore the tunnel was torn down.
Capabilities read is required for DP tunnels to work properly.

> And when thunderbolt.ko loads (or maybe only once userspace pokes it ?)
> and the i915.ko driver has not claimed the DP connection then the above
> message is logged and Linux does not see the DP attached display(s).
> 
> Building i915.ko into the initramfs works around this, but there
> seems to be an assumption on the kernel side about things happening
> in a certain order during boot which there should not be.

Right but as above capabilities read is required by the specs and we cannot
keep the DP tunnels up forever to consume power (and there is also
complication with add-in-cards that don't have all DP INs connected).

You can pass "thunderbolt.dprx_timeout=-1" (or some number or seconds) to
work it around.