iMX8MP LVDS Display LVDS Channel 0

Technical Support
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1

Can somebody please give a concrete device tree example of how to get an LVDS output on SODIMM pins 88,90 CLK 94,96 D0 100,102 D1 106,108 D2 112,114 D3?

I don’t know the precise resolution etc, but I would just like to see any signal output on these pins?

Please reply with a concrete DT example :slight_smile:

2

Hi @eoin_oc1 !

You are talking about the native LVDS of Verdin iMX8M Plus modules, right? Please be aware that this interface does not have family compatibility guarantee. The recommended way to have an LVDS interface and keep compatibility with other Verdin modules is to use a MIPI DSI to LVDS bridge IC. Reference: Verdin iMX8M Plus | Toradex Developer Center

About the native LVDS, please check the article below. There you will find a table with device tree overlays for Verdin iMX8M Plus using the Mezzanine, which exposes the native LVDS interface. You can check both the single channel and the dual channel overlays on Toradex’s overlay repository (also listed in the article below).

Let us know if this helps you :slight_smile:

Best regards,

3

I have been looking through examples for days now but no luck, that is why I would like a concrete example of how to get LVDS output on the pins I mentioned above. I am using the Verdin iMX8MP and would like to verify if I can get some display signals out on those pins.

Please give me a concrete precise example if you can :slight_smile:

4

Hi @eoin_oc1 !

From the default device tree files of Verdin iMX8M Plus and the device tree overlays mentioned, you have a concrete example/use case that will make an LVDS display functional when using the modules, the Verdin Development Carrier board and the Verdin iMX8M Plus Mezzanine.

I am not sure I understand your request. Could you please explain?

Best regards,

5

The closest example I found was this (verdin-imx8mp_mezzanine-lvds-single-channel_overlay.dts « overlays - device-tree-overlays.git - Sources for Device Tree Overlays)

I copy pasted this into my top level device tree, compiled and deployed to the target, but still no signals on the LVDS pins and no fb device when I look in /dev.

I would like to know exactly what lines of code I need to put in my DT file to get some signals out on LVDS channel 0

6

after piecing together 2-3 bits of other DT examples, I finally managed to get some signals on the pins I wanted.
My relevant DT changes looks like this now:

&gpu_2d {
	status = "okay";
};

&gpu_3d {
	status = "okay";
};

&lcdif2 {
	status = "okay";
};

&ldb {
	status = "okay";
};

&ldb_phy {
	status = "okay";
};

&mix_gpu_ml {
	status = "okay";
};

&ml_vipsi {
	status = "okay";
};

&panel_lvds {
        status = "okay";
        data-mapping = "vesa-24";
        width-mm = <199>;
        height-mm = <112>;
        panel-timing {
                clock-frequency = <60000000>;
                hactive = <1280>;
                hback-porch = <148>;
                hfront-porch = <88>;
                hsync-len = <44>;
                vactive = <720>;
                vback-porch = <36>;
                vfront-porch = <4>;
                vsync-len = <5>;
        };
};
7

Hi @eoin_oc1 !

Thanks for the feedback!

Could you please list the 2-3 device tree examples that inspired you? This way other people interested in the same topic could also benefit from the examples you found :slight_smile:

And, please, also don’t forget to mark the relevant message as the solution :wink:

Best regards,

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