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Omap Blaze tablet 2 LCD program

Darren Huang
Prodigy 60 points

Hi,

I used omap blaze-tablet2 with 4AI.1.4-P1 android code, and I want to modify lcd driver for testing RGB666 output via modify tc358765 DSI to LVDS bridge driver, when I modify pixelsize form 24 to 18 in board-44xx-tablet-panel.c, means the output pixel format is RGB666. After I rebuilt and download the code, the 1-2 pixel arifact will appear on the rigt side of the display panel as below, is there something wrong??

Thanks a lot.

Darren

 

 

  • 0
    TI__Prodigy 245 points

    Hi Darren,

    I do not have the answer but I do not think that changing the pixelsize parameters to RGB18 will output RGB18 pixels at the DSI I/F. Maybe the DISPC will ouput RGB18.
    Do you know what DISPC/DSI settings are impacted by this parameter
    Thanks

    Erwan

  • 0 in reply to Erwan Petillon
    TI__Expert 4120 points

    Hi Darren,

    I completely agree with Erwan that it is no as simple as changing the pixel size on board file. As per my discussions with our R & D team expert Archit, you have to take care of the following aspects in order to enable complete support for RGB18.

    1. DISPC has TFT data lines for R, G, B. You need to configure to use only 6 data lines per channel (R, G & B)

    2. DSI driver's video port has a field to specify pixel size which needs to be configured to 18 as opposed to 24.

    3. LVDS driver also needs to be configured accordingly to inform that only RGB18 is the input.

    Moreover, since the amount of data per frame has been reduced, you can push the clock down by configuring the LCD driver accordingly.

    Thanks & Best Regards,

    Venkat

  • 0 in reply to Venkat Ramana Peddigari
    TI__Prodigy 245 points

    Darren,

    I will just add to Venkat comments
    4. DSI I/F has to be set to send RGB18 long packet, you will have to determine new DSI porch timings and align it with the DISPC porch for a correct synchronisation.
    It is not an easy task.
    Thanks

    Erwan

  • 0 in reply to Erwan Petillon
    Prodigy 60 points

    Hi Erwan and Venkat,

    Thanks a lot for replies. Depends on your suggestions, I will check the code and try to improve DSI I/F output for RGB18 pixel format.  

    Darren

  • 0 in reply to Darren Huang
    Prodigy 60 points

    Hi Erwan and Venkat,

    I check Dispc TFT data lines and DSI driver's video port pixel size, and then configure data lines to 18, and configue pixel size to 18, then 1-2 pixel artifact still appear. The artifact caused by  DSI interface timing as you said. I finally fine tune the front proch, back proch and Hsync, the atifact was solved after fine tune the interface timings, thanks for the help.

    Darren

  • 0 in reply to Darren Huang
    TI__Expert 4120 points

    Hi Darren,

    Good to see that the issue is resolved. Thanks for giving us the update and pointers to address the artifact by modifying the interface timings accordingly. It is good to know and would be useful inputs for others.

    Could you please check the verify answer to close this post.

    Best Regards,

    Venkat