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Linux/DS90UH949-Q1: DS90UH949-Q1, black vertical lines on the image

Angelo Dureghello12
Prodigy 110 points
Part Number: DS90UH949-Q1

Tool/software: Linux

Dear all,

i am trying to have a good image as output on a 1280x480@60 screen from KOE.

The path is :  Linux-> HDMI controller -> DS90UH949-Q1 -> fpd link cable (single link) -> deserializer UB928 -> lvds display KOE 1280 x 480

The display timing specs are:  43,2 mhz pixel clock, 40 clk cycles invalid data before the image line, 40 clk cycles invalid after the image line, verticals are 30 lines before the frame, and 20 after.

After some black magic to find proper videomode in linux for this resolution, i have the following result:

The lake image is perfect, even if doesn't seems from the above image, but i am wondering now about the vertical black lines, may be generated by some wrong serializer setting or, i still have to tune better the linux side videomode and blanckings (synch porch etc) ?

Thanks for the support,

Angelo

  • 0
    TI__Genius 11340 points

    Hi Angelo,

    The black lines seem to appear at a set frequency, which indicates that there is some timing issue. You should verify that the HDMI source is able to meet the timing requirement of your display. You should also check data enable at the the black lines so make sure it's on.

    Best,

    Jiashow

  • 0 in reply to Jiashow Ho
    Prodigy 110 points

    Hi Jiashow, 

    thanks for your reply.

    The HDMI source reports:

    Variety of video resolutions and formats
    • Supports up to 4k2k at 60Hz resolution
    • 25-600Mhz pixel clk
    • Supports 8, 10, 12, and 16bpp
    • Supports RGB,YCbCr422,YCbCr420 formats

    So should be able to keep this resolution.

    Going ahead investigating,

    Angelo

  • 0 in reply to Angelo Dureghello12
    Prodigy 110 points

    Hi,

    i verified enabling the test pattern on the 949, that the image on the screen is without any vertical black line,

    i can see all the colored vertical bars, even if only in the first quarter of screen. While i can see the gradient pattern all over the screen, perfectly.

    At this point, fpd-link, cable, 928 deserializer seems excluded as cause of the issue.

    Could at this point considering this as a limitation of the source ? (in the meantime i opened a support request on the source side),

    Regards,

    angelo

  • 0 in reply to Angelo Dureghello12
    TI__Genius 11340 points
    Hi Angelo,

    Were the test pattern you generated the same resolution as the display (1280x480)? If so, it seems like the problem is with the source.

    Best,
    Jiashow