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AM623: USB DRD mode and DRP

Koichiro Tashiro
Mastermind 22945 points
Part Number: AM623
Other Parts Discussed in Thread: TPS25751, SK-AM62B-P1

Tool/software:

Hi,

My customer is planning to use USB in DRD mode as well as DRP.
In Linux kernel device tree, dr_mode is set as "otg".
Please see below schematics around USB for your reference.
USB schematics.xlsx

Questions:
Q1) Is it possible to use the same USB port for both DRD and DRP?
Q2) If yes, DRP control is done by PD controller (TPS25751), so there is no configuration needed on SoC side?

Please let me know if you need further information from the customer.

Thanks and regards,
Koichiro Tashiro

  • 0
    TI__Guru**** 171151 points

    Hi Tashiro-san,

    By DRP, do you mean the AM62x platform can source or sink power? If so I am unable to comment on this, since it is purely of PD controller design and has nothing to do with AM62x device. The USB0 port design on SK-AM62B-P1 can only sink power.

  • 0 in reply to Bin Liu
    Prodigy 100 points

    Hi Bin Liu

    Mr. Tashiro of TI Japan asked me to reply to you, so I would like to ask a question.

    I am considering using the attached configuration, and the Type C connector can be used as DRD or DRP.

    When used with DRP, the PD Driver will automatically control it, so I think the CPU will not know the status.

    So,

    -Is it possible to use the attached circuit as DRP or DRD?

    -I have only set the DRD for the CPU, but for the DRP, is it necessary to set the CPU for USB in addition? (Excluding the settings for the PD driver)

    As for the CPU settings, I have only set dr_mode to "otg" to set it to DRD in the kernel device tree.

  • 0 in reply to SHUNGO MIYATA
    TI__Guru**** 171151 points

    Hi Miyata-san,

    SHUNGO MIYATA said:
    -Is it possible to use the attached circuit as DRP or DRD?

    I checked the circuit diagram with the SK-AM62B-P1 schematics, they are both similar. So yes your design supports AM62x USB1 in DRD mode.

    SHUNGO MIYATA said:
    but for the DRP, is it necessary to set the CPU for USB in addition?

    I don't understand the question, please elaborate. DRP is about power delivery - sourcing or sinking power, it shouldn't be related to the USB function on CPU (AM62x).

    SHUNGO MIYATA said:
    As for the CPU settings, I have only set dr_mode to "otg" to set it to DRD in the kernel device tree.

    Yes, setting dr_mode = "otg" makes the AM62x USB interface to work in either host or device mode based on the role negotiation.

  • 0 in reply to Bin Liu
    Prodigy 100 points

    Hi Bin Liu

    I appreciate your response.

    >I don't understand the question, please elaborate. DRP is about power delivery - sourcing or sinking power, it >shouldn't be related to the USB function on CPU (AM62x).

    When a user connects a USB-PD device that supports DRP (Dual Role Power), the DP and DM lines configured for DRD (Dual Role Data) will also be connected. Is it okay not to worry about this?

    Could this cause any unexpected behavior?

  • 0 in reply to SHUNGO MIYATA
    TI__Guru**** 171151 points

    Hi Miyata-san,

    SHUNGO MIYATA said:
    When a user connects a USB-PD device that supports DRP (Dual Role Power), the DP and DM lines configured for DRD (Dual Role Data) will also be connected. Is it okay not to worry about this?

    I don't see any problem with AM62x, since it is up to the PD companion device, which takes care of DRD and PD communication, to tell AM62x USB to transition to host or device mode. But I don't know if it would be a problem for the PD companion device, since this forum only supports processors (AM62x in this case).