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SN65DSI86 - Link training question

Other Parts Discussed in Thread: SN65DSI86

Hello all,

I'm studing eDP and this SN65DSI86 seems to be suitable to test my design. I got some questions related to a Main Link Training when I read the training part in a datasheet of SN65DSI86.

To send a link training pattern, based on my understanging, I need to choose the one of 4 methods (manual/fast/semi-auto/redriver semi-auto) through the software. Then, for the receiver, how can the receiver recognize the difference among full/fast/no link training?

I know there is no AUX handshake for fast/no link training during training period. Then, does it means that the receiver will only receive training pattern (or just idle/normal video data pattern for no link training mode) through Link channel? If so, should the receiver check whether it is full link training or fast link training by using existance of AUX transaction?

I am very glad if there are some tips to recognize those three trainings.

Have a nice week!

Regards,

Jongmun

  • Hello Jongmun,

    Link Training starts when the DP transmitter writes the link configuration and sets the Link Training Pattern to the Link Configuration Field of the DPCD. Link training is expected to complete within 10ms. All devices must support TPS1 and TPS2. An HBR2 capable device must also support TPS3. A device not capable of HBR2 is recommended to support TPS3. A downstream device that is capable of supporting TPS3 must advertise this
    capability by setting the TPS3_SUPPORTED capability bit in DPCD 00002h. An upstream device that supports TPS3 must inspect the TPS3_SUPPORTED bit in the attached downstream device, and if it finds this bit is set, must transmit TPS3 during the Channel Equalization phase of link training (regardless of the speed at which the link is being trained). In all other cases, the upstream device must transmit TPS2 during the Channel Equalization phase of link training. If training without AUX CH handshake, then the use of TPS3 is determined either as the result of a previous training phase on the same connection, or by implementation dependent system configuration means.
  • Hello Joel,

    Thanks for replying. Is it right that both Full link Training and Fast Link Training should send TPS1 and TPS2/3 both (i.e. is there any case of sending just one training pattern like TPS2 only in Fast Link Training)?

    Also, can Fast Link Training be used for very first training? I mean, can Fast Link Training be used just after the source and the sink are connected?

    Additionally, I'm confusing about 'training without AUX CH handshake' what does it exactly mean? Does it mean that sink and source does not communicate anything by AUX channel during training? Or, is it that they do not send some specific DPCD information through AUX when training a link?

    Sincerely,
    Jongmun