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Linux/AM5708: HDMI 1920x1080 resolution not working

Vivek Panchal
Prodigy 250 points
Part Number: AM5708
Other Parts Discussed in Thread: TPD12S016

Tool/software: Linux

Hi All,

We have custom board based on am5708 and we have connected hdmi with it using dedicated hdmi lines. We also having lcd connection on lcd3 interface. we have two gpios(i.e., 6_8 and 6_9 for ls_oe and ct_cpd lines) and we are controlling that  from dts. when we got 1024x768 resolution in that case we got i2c master error print in kernel logs. we have also tried same thing with external gpio pullups same as am571x idk but in this case we got all resoultions and this time we have not get i2c master error. but with this configuration, we are not getting 1920x1080 resolution image on display and instead we are getting no signal on display.

Please let me know in case of more information needed.

Thanks,

Vivek

  • 0
    TI__Guru**** 393215 points
    Hi,

    Please post the SDK version and log files.
  • 0 in reply to Biser Gatchev-XID
    Prodigy 250 points

    8357.dmesglogs.txtHi Biser,

    Thanks for the quick response. I am using meta-ti layer of yocto. kernel version is 4.4.41. please find attached dmesg logs with custom prints.

  • 0 in reply to Vivek Panchal
    TI__Mastermind 22776 points
    Are you saying that changing the gpios affects the results? If so, then probably you may have issues with those, either in SW or in HW. You need to get your schematics reviewed first.
  • 0 in reply to Manisha Agrawal
    Prodigy 250 points
    Hi Manisha,

    We are having two different cases as below,

    1) If we drive both gpios from dts then we are getting i2c master error and in this case we are getting maximum 1024x768 resolution in modetest output. But if I give 1920x1080 from uboot as bootargs then I am able to drive display on that resoultion and also getting that resolution in modetest output as userdef but still i2c master error comes.

    2) if we are not driving that gpios and if we make pulled up externally as we have in am571x-idk then i am not getting any i2c master error. i am getting all mode information in output of modetest but in this case i am getting "no signal" on display.

    please let me know in case of more information needed.

    Thanks,
    Vivek
  • 0 in reply to Manisha Agrawal
    Prodigy 250 points

    Hi Manisha,

    PFA HDMI schematic page for your reference.

  • 0 in reply to Vivek Panchal
    TI__Mastermind 22776 points

    I  have notified our HW apps engineer to review the schematics and provide feedback.

    You may have issue on the board with LS_OE gpio which is preventing the i2c to the monitor from working. Additionally, you may have some other issue on the board which degrades the HDMI signal, which then prevents higher pixel clocl modes from working. You can try different modes  to see if lower resoultion modes work or not.

  • 0 in reply to Manisha Agrawal
    Prodigy 250 points
    Hi Manisha,

    Below are the two different setups.

    1) we have pulled up Ct_hpd and LS_OE gpios externally same as did in am571x Rev 1.3B idk. In this case, we are not getting any i2c communication related error(i.e. , we are able to successfully getting all the supported modes from display. we have verified that using modetest output ) but display is not working. we are getting "No Signal" on display all the time.

    2) When CT_HPD and LS_OE connected and we drive them high using dts configuration. in this case, we are getting i2c master error and we are not able to get an mode related information . so may be omapdrm driver set default configuration with 1024x768 maximum resolution. in this case, we are able to get display working. if we set 1920x1080 resolution using uboot boot args then it is also working with that resolution and we are getting mode as userdef in output of modetest.

    so here are the issues,
    - in case 1, Why it is not working?
    - in case 2, why we are getting i2c master error ?

    Please let me know in case of any more information.
  • 0 in reply to Vivek Panchal
    Prodigy 250 points
    Hello,

    Is there any update on this ?

    Thanks,
    Vivek
  • 0 in reply to Vivek Panchal
    TI__Guru 59545 points

    Manisha ask me to look at your issue from a hardware perspective. While discussing your issue with her, she recommended I look for similarities to a problem found on one of our EVMs. I ask the person responsible for this EVM to review your post and provide insight to your issue. I was told the TPD12S016 device has been used on several EVMs and has been problematic on many of them. The current theory indicates the auto-direction detection circuit in the TPD12S016 device doesn’t work very good when heavily loaded.

     

    Maybe the TI team that supports the TPD12S016 device would have some suggestions. I recommend you search for the appropriate E2E forum that supports TPD12S016 and ask if them for suggestions.

     

    Regards,

    Paul

  • 0 in reply to peaves
    Prodigy 250 points
    Hello,

    Do we have any further update from EVM team? We are blocked on this.

    Thanks,
    Vivek
  • 0 in reply to Vivek Panchal
    TI__Mastermind 26175 points
    Vivek,
    have you posted the question on the forum supporting TPD12S016? that was the recommendation above....it looks like the problem is related to it...
  • 0 in reply to Rogerio Almeida
    TI__Guru 59545 points

    Your issue appears to be intermittent communications with the attached display. As mentioned in my previous reply, several EVMs using TPD12S016 have a similar problem. I have been told the problem is related to the auto-direction detection circuit in TPD12S016. Therefore, the problem is not related to AM5708 which is supported on the Sitara Processor Forum.

     

    You need to contact the Circuit Protect team at TI since they provide support for TPD12S016. I provided a link to the Circuit Protect Forum, https://e2e.ti.com/support/interface/circuit-protection

     

    Regards,

    Paul