We are developing a CCG4-based dock with PS8742 mux. We have dual ports for docking and using a passive DP-mux to select which video is selected to the DP-to-HDMI converter. We are using the 3.2.1 host SDK. Updated config.h and stack_params.h included.
When connecting laptop (Dell, Macbook, HP) using the Thunderbolt-enabled ports via get 2-lane video to work. (4k2k@30Hz)
When we connected e.g. Samsung or Huawei phone or using the DP-only USB-C ports on HP / Dell laptops, the laptops thinks that there are a monitor connected, but nothing shows up on the external moniitor and it is not properbly detected. For mobiles, it gives an error message that "HDMI cable is not properly connected".
Since we don't have any USB 3/Superspeed ports, we want to always force 4-lane DP as well. Looking at the I2C communication to the PS8742 is sends 0x0030 when connecting on both Thunderbolt and non-TB ports. PD Analyzer trace included and the configuration used for CCG4.
HPD works as it should.
We are speculating that there is a problem with the number of lanes, provisioning of PS8742 and Mode C/D/E selection here maybe?
Where should we modify in configuration file and CCG4 defines to force 4-lane DP (no USB SS) or could there be some other reason why it works on Thunderbolt ports but not pure DP USB Type-C ports? I hope you can spot the errors by looking at the attached files.