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LVDS Display Troubleshooting

NPal.2
Senior

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 ?

1 ACCEPTED SOLUTION

Accepted Solutions
PatrickF
ST Employee

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,

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.

View solution in original post

2 REPLIES 2
PatrickF
ST Employee

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,

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.

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