Re: [PATCH] thunderbolt: Keep Meteor Lake host routers powered in DP redrive mode

[Mika Westerberg]

Hi,

On Tue, Oct 06, 2026 at 10:06:43AM +0200, Hans van Essen via B4 Relay wrote:
> From: Hans van Essen <hans@xxxxxxxxxxxx>
> 
> When a DisplayPort Alt Mode (non-Thunderbolt) dock is connected to the
> USB4 port of an Arrow Lake-H system with the integrated Meteor Lake-P
> host router (8086:7ec2), the USB functions of the dock work but the DP
> AUX transfers time out and no monitor is detected. It only works if the
> port was used with a Thunderbolt dock before and the system was not
> powered off in between; suspend and warm reboot keep it working.
> 
> The Barlow Ridge host routers already have QUIRK_KEEP_POWER_IN_DP_REDRIVE
> so that the host router does not enter runtime suspend while the USB4
> port is in DP redrive mode. Apply the same quirk to the integrated
> Meteor Lake host routers. With this the driver logs "enter redrive mode,
> keeping powered" when the dock is plugged in and the monitors come up
> after a cold boot.

Yes, Barlow Ridge needs it but it's a special case. ARL should not need
this - its all routed internally so something else is wrong here.

Can you share full dmesg when this issue happens? Please add
thunderbolt.dydnbg=+p too although this really has nothing to do with TB if
the port is in redrive mode.