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how configuring TPS65982 and HD3SS460 in docking side work at DP 4x lanes?

George Tan
Prodigy 40 points
Other Parts Discussed in Thread: TPS65982

Hello Sir,

I am making a type-c docking board using TI solution, now it works fine with a type-c source, but DP 2x lanes +USB3 only.

I like the type-c docking board can be worked both DP modes 4x and 2x lanes. could give some helping?

and the type-c source can be worked fine with DP 4xlanes when using a Google type-c dongle.

Thanks,

George

  • 0
    TI__Mastermind 30280 points

    George,

    There are 2 ways to achieve 4x Lane mode operation for full 4K resolution:

    1. Alternate between 2x-Lane and 4x-Lane modes: If your product has an I2C Master available and you can detect the presence of a USB3 device, you can toggle between the 'C' (4-Lane) and 'D' (2-Lane) pin assignments by toggling the "Multi-Function Preferred" bit in the DP Capabilities Register (0x51) and then sending a PD Hard Reset to the DFP to re-negotiate all PD contacts with your new capabilities
    2. Support 4-Lane mode operation ONLY: Enable Pin Assignment 'C' only

    The Google Dongle supports Pin Assignment 'E' Only, which is also for 4-lane operation.

    NOTE: My screen shots are being re-used from the older Config Tool. The new Config Tool (v2.X) allows the same options in a different GUI format.

  • 0 in reply to Brian Berner
    Prodigy 40 points

    Hi Brian,

    It's great! now the board has worked to the C configuration of DP 4xlanes. (got resolution 4k/60hz) Thanks,

    but how do toggle the both mode between C and D by which GPIO pin? 

    Thanks again,

    George

  • 0 in reply to George Tan
    TI__Mastermind 30280 points
    George,

    As I described in Option 1, the only way to toggle between Pin Assignments 'C' & 'D' is driven by an I2C Master within the System.
    If there is an I2C Master on your PCB, it is simple to explain:

    In most cases, a Dock or a Laptop has a video "scalar" which is also an I2C Master.
    Since switching from 2K+USB3 to 4K mode is generally a User input, the implementation I have seen is a Push Button or Switch that tells the "Scalar" to switch modes, then the "Scalar" Writes to Reg. 0x51 of the TPS65982 and toggles the Multi-Function Preferred bit.
    Finally, the "Scalar" issues a PD Hard Reset 4CC command to the TPS65982 which will issue a Hard Reset on the CC line to re-establish a new connection using the opposite 2-Lane/4-Lane setting.

    Currently, this feature is not driven by a GPIO Input since there is not a generalized implementation we think will work in every system and the "Scalar"+TPS65982 both need to receive the information to change the resolution correctly.
  • 0 in reply to Brian Berner
    Prodigy 40 points

    Hi Brian,

    my board have not an I2C master now, but I have tried toggle the C and D mode via Aardvard adapter and TI interface tool. that's fine.

    I will add the feature on if modifying the board.

    Thanks for great supporting,

    George