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NPal.2
Visitor II
July 5, 2021
Solved

LVDS Display Troubleshooting

  • July 5, 2021
  • 1 reply
  • 2180 views

Hi all,

I am trying to bring a LVDS display up. Display: BOE EV121WXM-N10-1850. Datasheet: Link

Driving MPU : STM32MP1. I am using VisionSoM STM32MP1 based evaluation Kit. Link

The firmware changes required to make the device up are part of git: Link

I have made following changes in the dts files to support display:

kernel/stm32mp157a-visionsom-rgb-emmc-mx.dts and u-boot/stm32mp157a-visionsom-rgb-emmc-mx.dts has following changes :

 panel {
 
 compatible = "boe,ev121wxmn10", "simple-panel";
 
 backlight = <&backlight>;
 
 port {
 
 panel_in: endpoint {
 
 remote-endpoint = <&ltdc_out_rgb>;
 
 };
 
 };
 
 };

In case u-boot/stm32mp157a-visionsom-rgb-emmc-mx-u-boot.dtsi

 panel {
 
 display-timings {
 
 timing0: timing0 {
 
 clock-frequency = <74250000>;
 
 hactive = <1280>;
 
 vactive = <800>;
 
 hfront-porch = <48>;
 
 hback-porch = <80>;
 
 hsync-len = <32>;
 
 vback-porch = <15>;
 
 vfront-porch = <3>;
 
 vsync-len = <5>;
 
 hsync-active = <0>;
 
 vsync-active = <0>;
 
 de-active = <0>;
 
 pixelclk-active = <1>;
 
 };
 
 };
 
 };

Here i have added panel settings to support the above display. Now the port which i have out on the board is RGB. I have used RGB to LVDS converter DS90C385A. Since I am trying to drive LVDS display.

The issue i am facing is that , I am unable to drive the display. Nothing is coming up.

Queries:

  1. The settings which i have made , are those correct ?
  2. What additional changes I might need to make , if i am missing any?
  3. What can be potential failure points in this ?
  4. What is the correct way to drive LVDS display? Is this correct way to do this ?

    This topic has been closed for replies.
    Best answer by PatrickF

    Hi,

    I'm not specialist, maybe asking Somlabs could be useful for support on their DT.

    Probably missing some &ltdc node modifications to define that the panel is connected to it.

    Example with external si9022 RGB2HDMI transceiver could be helpful : https://wiki.st.com/stm32mpu/wiki/LTDC_device_tree_configuration

    Regards,

    1 reply

    P
    PatrickFAnswer
    Technical Moderator
    July 6, 2021

    Hi,

    I'm not specialist, maybe asking Somlabs could be useful for support on their DT.

    Probably missing some &ltdc node modifications to define that the panel is connected to it.

    Example with external si9022 RGB2HDMI transceiver could be helpful : https://wiki.st.com/stm32mpu/wiki/LTDC_device_tree_configuration

    Regards,

    N
    NPal.2Author
    Visitor II
    July 7, 2021

    Thanks @PatrickF​ for the response , will take a look into it.

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