TPS65982: No USB 2.0 in 4-lane DP mode

Eriks Austrums

Part Number: TPS65982

Hello, i have a question about USB 2.0 lines in DisplayPort mode. While we are not in DisplayPort mode we have and can use USB 2.0 lines, but when we enter in DP mode, they are gone and don't show up.

Is there a reason for this? Does this work as expected or am i missing something? I dont see a reason for USB 2.0 not working while in DisplayPort mode.

Any help is appreciated.

Kind regards, Eriks Austrums

over 5 years ago

0 Adam Mc Gaffin over 5 years ago

TI__Mastermind 30000 points

Hello Eriks,

Yes this seems to be expected behavior. Based on my understanding, you must exit out of USB2 mode when when entering into an alternate mode such as display port

0 Eriks Austrums over 5 years ago in reply to Adam Mc Gaffin

Intellectual 675 points

But shouldn't DisplayPort and USB2.0 coexist ? Just as DisplayPort and USB3.0 and Aux channel etc. ?

0 Eriks Austrums over 5 years ago in reply to Eriks Austrums

Intellectual 675 points

After looking into the specification i found this, USB 2.0 and USB PD are available in all configurations. So the question is, does TPS65982 support this and if yes , what would the problem be that it doesn't work?

0 Adam Mc Gaffin over 5 years ago in reply to Eriks Austrums

TI__Mastermind 30000 points

Hello,

Apologies for the late reply. Yes, the TPS65982 is capable of supporting this as all the TPS65982 does is negotiate the alternate mode that the system enters into and mux the USB2 lines depending on the port orientation

0 Eriks Austrums over 5 years ago in reply to Adam Mc Gaffin

Intellectual 675 points

Yes, thank you Adam,

After a little more research and testing , it looks like , that the USB2.0 is active with 4 lane DP if the device is a sink. And there is a weird behavior if USB RP and USB EP are both enabled, that is, the USB doesn't show up if both are enabled. Even tho you say it should work if both are enabled , from e2e.ti.com/.../577331

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TPS65982: No USB 2.0 in 4-lane DP mode