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Linux/AM5728: HDMI out not working in custom board

Marka Reddy
Expert 1260 points
Part Number: AM5728
Other Parts Discussed in Thread: TPD12S015

Tool/software: Linux

Hi,

we have developed a custom board by taking AM5728 EVM as a reference. In the HDMI out section we have not used the encoder/equilizer that was used in the EVM, instead we used ADV 3003 IC. Moreover we have not connected the HDMI i2c lines to connector.

Is ti mandatory to connect I2C lines to connector?

what are the changes that can be done in device tree file to bypass HDMI ic used in the EVM?

Regards,

Marka reddy

  • 0
    Expert 1260 points
    hi,
    can anyone please help me in solving the above issue
    Regards,
    Marka reddy
  • 0 in reply to Marka Reddy
    TI__Mastermind 22946 points

    Hi Marka,

    Please expect response in next couple of days. 

    Regards,

    Manisha

  • 0 in reply to Manisha Agrawal
    TI__Mastermind 46460 points

    Marka,

    What are you trying to do?  The AM5728 device contains a fully functional HDMI interface.  The ADV3003 is a signal regenerator.  Why have you implemented this device?  As you see in the EVM schematic, the HDMI pairs from the AM5728 can be directly connected to the HDMI display.  Transient protectors are needed if you are connecting to the HDMI display through a connector and cable.

    Similarly, related to I2C, what is you application?  The I2C link is needed as a control channel to negotiate options with the display.  If you have a fixed installation, then this is not needed but the HDMI software driver will need to be modified to operate only in a fixed mode.  Alternately, if you are connecting to standard HDMI panels over a cable, then the I2C signaling will be needed.

    Tom

  • 0 in reply to Tom Johnson 16214
    Expert 1260 points
    Tom,
    Thank you
    1. We are connecting the HDMI display through connector and a long cable . This is the reason to include ADV3003 buffer in between AM5728 HDMI out and connector.
    2. We have a fixed installation for HDMI display. we learnt that by configuring CONFIG_DRM_LOAD_EDID_FIRMWARE to yes we can re direct the driver not to probe EDID data on I2C lines but use the internally supplied one. Is this the correct approach?
    3. Since we are not using the tpd12s015, please guide us to bypass this in device tree file

    Marka
  • 0 in reply to Marka Reddy
    TI__Mastermind 46460 points

    Marka,

    Since we have discussed the hardware implementation issues and now this appears to be a Linux implementation issue, I will forward this to that team.

    Tom

  • 0 in reply to Tom Johnson 16214
    TI__Mastermind 22946 points
    Hi Marka,

    There's duplicate e2e post raised by your company on the software related queries and I am responding it over there
    e2e.ti.com/.../2791059

    Will close this thread and we can continue discussing software related queries on other thread.

    Regards,
    Manisha