APPLIED[U]: [PATCH 0/4][SRU][U/L/K] Fix Monitor lost after replug WD19TBS to SUT port with VGA/DVI to type-C dongle Edit

[Andrea Righi]

On Thu, Jun 01, 2023 at 09:51:24AM +0800, Koba Ko wrote:
> BugLink: https://bugs.launchpad.net/bugs/2021949
> 
> [Impact]
> Enabling CL1 (Controller Low Power) states during discovery of existing tunnels established by the system firmware can interfere with the operation of those tunnels.
> The DisplayPort tunnel establishment timeout of 1.5 seconds can be insufficient for some docking stations, leading to blank displays.
> 
> [Fix]
> CL1 states are now not enabled during discovery of existing tunnels. The TMU settings also remain unchanged.
> The timeout is increased to 3 seconds to allow more time for the DisplayPort connection manager handshake, fixing the issue of displays remaining blank.
> 
> [Test Cases]
> 1. plug docking station on the host
> 2. bring up the host and get into desktop.
> 3. flip docking station's cable.
> 4. check if the external monitor works well
> 
> [Where problems could occur]
> Low, If the handshake actually requires even more than 3 seconds in some cases, the timeout may still need to be increased further.
> 
> [Misc]
> Jammy needs more patches to enable the thunderbolt CLx and the SRU will be a huge,
> so skip Jammy.

Patches 2/4 and 3/4 applied to mantic/linux-unstable.

Thanks,
-Andrea